Line 3 did something rare for a pipeline that exports Canadian crude: It got built

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A look at the Line 3 oil pipeline — what it does and doesn't do, and what it's damaged

Alexander Panetta · CBC News · Posted: Oct 11, 2021 4:00 AM ET | Last Updated: 4 hours ago

The Enbridge Line 3 pipeline seen during construction in Park Rapids, Minn., on June 6. (Nicholas Pfosi/Reuters)

A phenomenon recently unfolded that represents a rarity in this era of vocal opposition to Canadian fossil-fuel projects.

A major pipeline project exporting oil from Canada was just completed and it began operating with relatively little national attention.

The Line 3 project attracted much less scrutiny than Keystone XL from American protesters, media and politicians.

It didn't even appear to be the top pipeline story in Canada last week — that distinction likely belonged to Line 5, which is escalating as a political irritant between Canada and the U.S.

Yet Line 3 was up and running on Oct. 1, adding 370,000 barrels per day in new exports from Alberta to Wisconsin, which is more than half the output the scrapped Keystone XL project was supposed to achieve.

• Tea and sympathy: Canadian frigate helps Royal Navy solve a high-seas catering crisis

As a result, Canadian oil exports to the United States just reached one of their highest-ever weekly volumes, according to the latest U.S. numbers.

However, the process of getting the pipeline built through Minnesota illustrated the risks of completing such a project in this era.

The project's legacy

Its legacy includes an environmental disaster, a controversial arrangement with police, and legal fights and protests that are ongoing.

So was it a game-changer — either for Alberta's oil sector or for the climate?

Winona LaDuke, an Indigenous activist, economist and former Green Party U.S. vice-presidential candidate, seen here at a protest in Park Rapids, Minn. back in June, says she was arrested multiple times for protesting the Line 3 project. (Nicholas Pfosi/Reuters)

An energy economist at the University of Alberta doubts it will have a significant impact on either oilsands investment or on greenhouse gas emissions.

Andrew Leach has a new paper out in the Alberta Law Review that suggests we're unlikely to see any brand new oil export pipelines ever built from Canada. 

This particular project by Alberta-based Enbridge involved changes to a line built in 1968 that had seen its capacity erode over time. The renovation restored that original capacity, installed a slightly wider pipe and altered parts of the route.

Leach said the project is unlikely to prompt a flood of new investment in Alberta.

A map of the Line 3 route. The new project refurbished and expanded the capacity of the aging pipeline and altered part of the original route. (CBC News)

Pipelines are, in his estimation, a sideshow to the main factor that drives investment decisions in the oilsands: Global oil prices.

For example, he says, pipeline shortages or availability might affect the value of a barrel of oil by at most $12, but oil prices, on the other hand, have swung by multiple times that amount in recent years.

"Oil prices are the big one," he said.

"The overall oil market is weaker than it used to be, which is most of what's driving the … declining growth in oilsands production." 

This project did, however, leave an impact in Minnesota. 

Massive damage to aquifer

That impact includes a massive amount of damage to a water source in the northeastern part of the state. An aquifer was punctured during construction and that has led to a leak of many millions of gallons of groundwater. 

Enbridge has been fined $3.32 million by the state of Minnesota and ordered to repair the damage.  

The Minnesota Department of Natural Resources found that the company failed to follow environmental laws and did not respect the conditions of its construction plan when it dug a trench far larger than allowed.

Demonstrators locked themselves to Enbridge equipment during a protest against the pipeline in Hubbard County, Minn, back on June 7. Enbridge spent more than $3 million on a fund that paid Minnesota police forces to protect the project. (Nicholas Pfosi/Reuters)

The company incurred another cost that speaks to local opposition to its work: paying for policing.

Enbridge was ordered by state regulators to pay into an escrow account that would fund Minnesota police operations to protect the project. It was a condition for Enbridge receiving state approval for its project in 2018. 

The latest figures provided to CBC News by the Minnesota Public Utilities Commission last week said the account had paid out $3.1 million.

This has drawn outrage from activists and critical coverage from some media in the U.S. and U.K. 

"It's brutal," said Winona LaDuke, an economist, ecologist, Indigenous activist, and two-time U.S. vice-presidential candidate for the Green Party.

"It's brutal what they've done to our society. It's brutal what they've done to our legal system and regulatory system. And it's brutal what they've done to our environment and to Indigenous people. Nobody gets a tiara for putting in this pipeline. This is horrible."

The payments to police

In an interview with CBC News, LaDuke said she herself was arrested several times, charged with trespassing and unlawful assembly, and spent three nights in jail while protesting Line 3.

She said there have been 900 arrests over the project.

LaDuke accused Minnesota police of "prostituting" themselves, being paid by a foreign company to arrest American protesters.

Enbridge's response to opponents: Oil will still be used for years — for transportation and heating, and for manufacturing products such as medical equipment, seen here. New pipelines, the company says, are the safest and cleanest way to transport it. (Kathleen Flynn/Reuters)

As for the company, she said: "They've really ... made a mess of northern Minnesota. They should not be proud of themselves. Canada should not be proud of Enbridge."

She said Canada should be having a real conversation about whether the oil economy is worth having its companies arrest foreign citizens.

Company: 'We are very proud' of project

The company vigorously defended the project. 

In an email exchange with CBC News, it said this newer, safer pipeline, with thicker steel and more advanced coating than the 1968 original, will more securely carry oil — oil that people still rely on to drive, cook and build products, from medical supplies to winter coats.

"This was the largest project in our company's history, and we are very proud of that achievement," Enbridge spokesperson Jesse Semko said in an email.

As for the relationship with Minnesota police, he said the company was required to pay into the fund by state regulators.

And he said that to receive payments, local authorities had to submit written, itemized requests for reimbursement to the state-appointed manager of the fund.

He said police made decisions on law enforcement after receiving tips from company employees working on the route.

"Our security workers were armed only with cellphones," Semko wrote. "They contacted police when protesters endangered themselves or our workers."

Workers attempt to cut activists free after they chained themselves to a speedboat during demonstrations against Line 3 in Park Rapids, Minn., on June 8. (Nicholas Pfosi/Reuters)

Construction is over. But opposition isn't.

There will be several days' worth of protests this week in Washington against this and other pipeline projects and Line 3 opponents are still hoping to block it in tribal and federal courts.

 

Artificial intelligence suggests a new narrative for the Out of Africa process

by Estonian Research Council

West African migrations. Credit: Saoni Banerji/Wikimedia

Researchers from Estonia and Italy developed an innovative method by combining neural networks and statistics. Using this newly developed method, they refined the "Out of Africa" scenario. The researchers claimed that the African dynamics around the time of the Out of Africa expansion are more complex than previously thought.

Archaeologists and geneticists agree that all modern humans originated somewhere in Africa around 300 thousand years ago. The population movement that colonized the rest of the globe occurred approximately 60-70 thousand years ago. Both Y-chromosomal data (which follows patrilineal lineage) and the Mitochondrial genome (which follows the matrilineal line) agree on this. However, the exact relationship between the people who left Africa and the human populations currently inhabiting the continent is not fully understood.

A simplistic model would see the first phase of within-Africa population subdivisions, followed by a separation between the ancestors of modern Eurasians and the ancestors of modern East or North-East Africans. New research on this topic, recently published in the American Journal of Human Genetics, argues that the Out of Africa expansion was preceded by a significant population turnover from East to West Africa. This event likely homogenized West and East Africans. This turnover, which may account for up to 90% of the contemporary West African gene pool, increased the affinity between West Africans and Eurasians. This event better explains the lower bound (~60 thousand years ago) inferred from genetic data for the separation time between Africans and non-Africans.

"A similar hypothesis was proposed before for the Y chromosome. But this is the first time we demonstrated it for autosomal DNA," said Francesco Montinaro, a Lead author in this study from the University of Bari. Autosomal DNA comes from both parents, instead of Y-chromosome or Mitochondria, which comes only from one of our parents.

"It is fascinating to see how our understanding of the human past becomes ever more complex and detailed. Our new model can give us a clue why West Africa shows such a young separation time from the out of Africa populations," said Vasili Pankratov, a lead co-author from the University of Tartu.

Researchers shed new light on the origins of modern humans

More information: Revisiting the Out of Africa event with a Deep Learning approach, American Journal of Human Genetics (2021). doi.org/10.1016/j.ajhg.2021.09.006

Journal information: American Journal of Human Genetics 

Provided by Estonian Research Council

 

What makes us human? The answer may be found in overlooked DNA

by Cell Press

Graphical abstract. Credit: https://doi.org/10.1016/j.stem.2021.09.008

Our DNA is very similar to that of the chimpanzee, which in evolutionary terms is our closest living relative. Stem cell researchers at Lund University in Sweden have now found a previously overlooked part of our DNA, so-called non-coded DNA, that appears to contribute to a difference which, despite all our similarities, may explain why our brains work differently. The study is published in the journal Cell Stem Cell.

The chimpanzee is our closest living relative in evolutionary terms and research suggests our kinship derives from a common ancestor. About five to six million years ago, our evolutionary paths separated, leading to the chimpanzee of today, and Homo Sapiens, humankind in the 21st century.

In a new study, stem cell researchers at Lund examined what it is in our DNA that makes human and chimpanzee brains different—and they have found answers.

"Instead of studying living humans and chimpanzees, we used stem cells grown in a lab. The stem cells were reprogrammed from skin cells by our partners in Germany, the U.S. and Japan. Then we examined the stem cells that we had developed into brain cells," explains Johan Jakobsson, professor of neuroscience at Lund University, who led the study.

Using the stem cells, the researchers specifically grew brain cells from humans and chimpanzees and compared the two cell types. The researchers then found that humans and chimpanzees use a part of their DNA in different ways, which appears to play a considerable role in the development of our brains.

"The part of our DNA identified as different was unexpected. It was a so-called structural variant of DNA that were previously called "junk DNA," a long repetitive DNA string which has long been deemed to have no function. Previously, researchers have looked for answers in the part of the DNA where the protein-producing genes are—which only makes up about two percent of our entire DNA—and examined the proteins themselves to find examples of differences."

The new findings thus indicate that the differences appear to lie outside the protein-coding genes in what has been labeled as "junk DNA," which was thought to have no function and which constitutes the majority of our DNA.

"This suggests that the basis for the human brain's evolution are genetic mechanisms that are probably a lot more complex than previously thought, as it was supposed that the answer was in those two percent of the genetic DNA. Our results indicate that what has been significant for the brain's development is instead perhaps hidden in the overlooked 98 percent, which appears to be important. This is a surprising finding."

The stem cell technique used by the researchers in Lund is revolutionary and has enabled this type of research. The technique was recognized by the 2012 Nobel Prize in Physiology or Medicine. It was the Japanese researcher Shinya Yamanaka who discovered that specialized cells can be reprogrammed and developed into all types of body tissue. And in the Lund researchers' case, into brain cells. Without this technique, it would not have been possible to study the differences between humans and chimpanzees using ethically defensible methods.

Why did the researchers want to investigate the difference between humans and chimpanzees?

"I believe that the brain is the key to understanding what it is that makes humans human. How did it come about that humans can use their brain in such a way that they can build societies, educate their children and develop advanced technology? It is fascinating!"

Johan Jakobsson believes that in the future the new findings may also contribute to genetically-based answers to questions about psychiatric disorders, such as schizophrenia, a disorder that appears to be unique to humans.

"But there is a long way to go before we reach that point, as instead of carrying out further research on the two percent of coded DNA, we may now be forced to delve deeper into all 100 percent—a considerably more complicated task for research," he concludes.Scientists discover how humans develop larger brains than other apes

More information: Pia A. Johansson et al, A cis-acting structural variation at the ZNF558 locus controls a gene regulatory network in human brain development, Cell Stem Cell (2021). doi.org/10.1016/j.stem.2021.09.008

Journal information: Cell Stem Cell 

Provided by Cell Press 

Fossils and ancient DNA paint a vibrant picture of human origins
A century of science has begun to explain how and where Homo sapiens and our kin evolved

A century ago, scientists knew almost nothing about our ancient ancestors, but have since discovered a wide range of relatives.
THE NATURAL HISTORY MUSEUM/ALAMY STOCK PHOTO


By Erin Wayman

SEPTEMBER 15, 2021 AT 10:30 AM


In The Descent of Man, published in 1871, Charles Darwin hypothesized that our ancestors came from Africa. He pointed out that among all animals, the African apes — gorillas and chimpanzees — were the most similar to humans. But he had little fossil evidence. The few known human fossils had been found in Europe, and those that trickled in over the next 50 years came from Europe and from Asia.

Had Darwin picked the wrong continent?

Finally, in 1924, a fortuitous find supported Darwin’s speculation. Among the debris at a limestone quarry in South Africa, miners recovered the fossilized skull of a toddler. Based on the child’s blend of humanlike and apelike features, an anatomist determined that the fossil was what was then popularly known as a “missing link.” It was the most apelike fossil yet found of a hominid — that is, a member of the family Hominidae, which includes modern humans and all our close, extinct relatives.

That fossil wasn’t enough to confirm Africa as our homeland. Since that discovery, paleoanthropologists have amassed many thousands of fossils, and the evidence over and over again has pointed to Africa as our place of origin. Genetic studies reinforce that story. African apes are indeed our closest living relatives, with chimpanzees more closely related to us than to gorillas. In fact, many scientists now include great apes in the hominid family, using the narrower term “hominin” to refer to humans and our extinct cousins.

In a field with a reputation for bitter feuds and rivalries, the notion of humankind’s African origins unifies human evolution researchers. “I think everybody agrees and understands that Africa was very pivotal in the evolution of our species,” says Charles Musiba, a paleoanthropologist at the University of Colorado Denver.

Paleoanthropologists have sketched a rough timeline of how that evolution played out. Sometime between 9 million and 6 million years ago, the first hominins evolved. Walking upright on two legs distinguished our ancestors from other apes; our ancestors also had smaller canine teeth, perhaps a sign of less aggression and a change in social interactions. Between about 3.5 million and 3 million years ago, humankind’s forerunners ventured beyond wooded areas. Africa was growing drier, and grasslands spread across the continent. Hominins were also crafting stone tools by this time. The human genus, Homo, arrived between 2.5 million and 2 million years ago, maybe earlier, with larger brains than their predecessors. By at least 2 million years ago, Homo members started traveling from Africa to Eurasia. By about 300,000 years ago, Homo sapiens, our species, emerged.

All in the family

Fossil finds suggest that many hominin species have lived over the last 7 million years (dates for each species are based on those finds), though researchers debate the validity of some of these classifications. The earliest purported hominins (purple) show some signs of upright walking, which became more routine with the rise of Australopithecus (green). Seemingly short-lived Paranthropus (yellow) was adapted for heavy chewing, and brain size began to increase in Homo species (blue).
H. THOMPSON

But human evolution was not a gradual, linear process, as it appeared to be in the 1940s and ’50s. It did not consist of a nearly unbroken chain, one hominin evolving into the next through time. Fossil discoveries in the ’60s and ’70s revealed a bushier family tree, with many dead-end branches. By some counts, more than 20 hominin species have been identified in the fossil record. Experts disagree on how to classify all of these forms — “Fossil species are mental constructs,” a paleoanthropologist once told Science News — but clearly, hominins were diverse, with some species overlapping in both time and place.

Even our species wasn’t always alone. Just 50,000 years ago, the diminutive, 1-meter-tall Homo floresiensis, nicknamed the hobbit, lived on the Indonesian island of Flores. And 300,000 years ago, Homo naledi was a neighbor in South Africa.

Finding such “primitive” species — both had relatively small brains — living at the same time as H. sapiens was a big surprise, says Bernard Wood, a paleoanthropologist at George Washington University in Washington, D.C. Those discoveries, made within the last two decades, were reminders of how much is left to learn.

It’s premature to pen a comprehensive explanation of human evolution with so much ground — in Africa and elsewhere — to explore, Wood says. Our origin story is still a work in progress.

Raymond Dart had a wedding to host.

It was a November afternoon in 1924, and the Australian-born anatomist was partially dressed in formal wear when he was distracted by fossils. Rocks containing the finds had just been brought to his home in Johannesburg, South Africa, from a mine near the town of Taung.

Raymond Dart recognized that the Taung Child (shown with Dart decades after its 1924 discovery) had both apelike and humanlike qualities. The find sparked the search for more hominin fossils in Africa.

SCIENCE HISTORY IMAGES/ALAMY STOCK PHOTO

Imprinted on a knobby rock about as big as an orange were the folds, furrows and even blood vessels of a brain. It fit perfectly inside another rock that had a bit of jaw peeking out.

The groom pressed Dart to get back on track. “My god, Ray,” he said. “You’ve got to finish dressing immediately — or I’ll have to find another best man.”

As soon as the festivities ended, Dart, 31 years old at the time, started removing the jaw from its limestone casing, chipping away with knitting needles. A few weeks later, he had liberated not just a jaw but a partial skull preserving the face of a child.

On February 7, 1925, in the journal Nature, Dart introduced the Taung Child to the world. He described the fossil as an ape like no other, one with some distinctly humanlike features, including a relatively flat face and fairly small canine teeth. The foramen magnum, the hole through which the spinal cord exits the head, was positioned directly under the skull, implying the child had an erect posture and walked on two legs.

Dart concluded that the Taung Child belonged to “an extinct race of apes intermediate between living anthropoids and man.” His italicized text emphasized his judgment: The fossil was a so-called missing link between other primates and humans. He named it Australopithecus africanus, or southern ape of Africa.

The Taung Child was the second hominin fossil discovered in Africa, and much more primitive than the first. Dart argued that the find vindicated Darwin’s belief that humans arose on that continent. “There seems to be little doubt,” Science News Letter, the predecessor of Science News, reported, “that there has been discovered on the reputed ‘dark’ continent a most important step in the evolutionary history of man.”

But Dart’s claims were mostly met with skepticism. It would take more than two decades of new fossil finds and advances in geologic dating for Dart to be vindicated — and for Africa to become the epicenter of paleoanthropology.

Hot spots

This map marks locations of some of human evolution’s biggest fossil discoveries. The search in Africa began in the 1920s. Yet there is still much of the continent left to explore, as paleoanthropologists have mostly focused on eastern and southern Africa.

A. The oldest known Homo sapiens fossils, dating to about 300,000 years ago, come from Jebel Irhoud in Morocco.

B. At the Toros-Menalla site in Chad, scientists found what may be the earliest known hominin, Sahelanthropus tchadensis.

C. Ethiopia’s Afar region hosts numerous sites, some stretching back more than 5 million years. Major finds include the early hominin Ardipithecus and Lucy.

D. Southern Ethiopia and northern Kenya hold a long hominin history, including Australopithecus fossils, some of the oldest known stone tools, early Homo fossils and early H. sapiens fossils.

E. Louis and Mary Leakey put Tanzania’s Olduvai Gorge on the map with discoveries of Paranthropus boisei and Homo habilis. The nearby Laetoli site preserves hominin footprints dating to 3.6 million years ago.

F. The Kabwe skull, the first hominin fossil found in Africa, came from a mine in Zambia in 1921.

G. South Africa’s limestone caves have yielded Australopithecus, Paranthropus and Homo fossils.

H. Quarry workers near Taung, South Africa, recovered the first Australopithecus fossil ever found.

I. At caves along coastal South Africa, scientists have recovered a rich record of H. sapiens activity, including what may be the earliest known drawing and other signs of symbolic behavior.
SOURCE: NATIONAL RESEARCH COUNCIL/UNDERSTANDING CLIMATE’S INFLUENCE ON HUMAN EVOLUTION 2010; ADAPTED BY E. OTWELL

Against the establishment

Unlike Darwin, many evolutionists of the late 19th and early 20th centuries had theorized that the human family tree was rooted in Asia. Some argued that Asia’s gibbons were our closest living relatives. Others reasoned that tectonic activity and climate change in Central Asia sparked human evolution. One naturalist even proposed that human origins traced back to a lost continent that had sunk in the Indian Ocean, forcing our ancestors to relocate to Southeast Asia.

And that’s where the best contender for an early human ancestor had been found. In the 1890s, a crew led by Dutch physician-turned-anthropologist Eugène Dubois had uncovered a skullcap and thigh bone on the Indonesian island of Java. The thick skullcap had heavy brow ridges, but Dubois estimated it once held a brain that was about twice as big as an ape’s and approaching the size of a human’s. The thigh bone indicated that this Java Man, later named Homo erectus, walked upright.

Europe had its own tantalizing fossils. Neandertals had been known since the mid-19th century, but by the early 20th century, they were generally thought to be cousins that lived too recently to shed much light on our early evolution. A more relevant discovery seemed to come in 1912, when an amateur archaeologist had recovered humanlike bones from near Piltdown, England; the site also contained fossils of extinct creatures, suggesting Piltdown Man was of great antiquity. Skull bones hinted he had a human-sized brain, but his primitive jaw had a large, apelike canine tooth.

Some experts questioned whether the skull and jaw belonged together. But British scientists embraced the discovery — and not just because it implied England had a role in human origins. Piltdown Man’s features fit with the British establishment’s view of human evolution, in which a big brain was the first trait to distinguish human ancestors from other apes.

So when Dart announced that he had found a small-brained bipedal ape with humanlike teeth in the southern tip of Africa, scientists were primed to be skeptical, says Paige Madison, a historian of science at the Natural History Museum of Denmark in Copenhagen. Scientists were also skeptical of Dart. While a student in London, he had earned a reputation as a “scientific heretic, given to sweeping claims,” according to a paper coauthored by a colleague.

But initial criticism focused mostly on practical concerns, says Madison, who has studied the skeptics’ reactions. “I found what they were actually saying on paper to be quite reasonable.”

A big problem: Dart’s fossil was of a 3- or 4-year-old child. Critics pointed out that a young ape tends to resemble humans in some ways, but the similarities disappear as the ape matures. Critics also complained that Dart hadn’t done proper comparative analyses with young chimps and gorillas, and he refused to send the fossil to England where such analyses could be done. This refusal irked the British old guard. “It was unpalatable to the scientists in England that the young colonial upstart had presumed to describe the skull himself,” one of Dart’s contemporaries later wrote, “instead of submitting it to his elders and betters.”

It’s hard not to wonder how the era’s colonialist and racist attitudes shaped perceptions. The Taung Child came to light at a time when eugenics was still considered legitimate science, and much of anthropology was devoted to categorizing people into races and arranging them into hierarchies. On the one hand, Western researchers tended to maintain the perverse notion that Africans are more primitive than other people, even less evolved. On the other, they wanted to believe Europe or Asia is where humans originated.

How these views influenced reactions to the Taung Child is not clear-cut. Many skeptics didn’t cite the fossil’s location as a problem, and some acknowledged humans could have evolved in Africa. But deep-seated biases may have made it easier for some researchers to reject the Taung Child and accept Piltdown Man, even though fossil evidence for that claim was also scant, says Sheela Athreya, a paleoanthropologist at Texas A&M University in College Station.

Newspapers worldwide followed the Taung Child controversy. And while fans sent Dart poems and short stories casting the child as a national hero, he also received letters from disapproving creationists.

Amid it all, Dart had convinced at least one well-known scientist. Robert Broom, a Scottish-born physician living in South Africa and an authority on reptile evolution, recognized that fossils of fully grown A. africanus individuals would be needed to confirm that the Taung Child’s humanlike qualities were retained in adulthood.

In the 1930s and ’40s, Robert Broom unearthed fossils in South African caves, including at Sterkfontein (shown), that helped convince skeptics that Australopithecus was a human ancestor.

NATURAL HISTORY, 1947 (LINDA HALL LIBRARY)

Broom began to find just that evidence in 1936 in caves not far from Johannesburg. Often taking the heavy-handed approach of detonating dynamite to free specimens, he amassed a collection of fossils representing both the young and the old. Limb, spine and hip bones confirmed South Africa was once home to a bipedal ape, and skull bones verified Dart’s inferences about A. africanus’ humanlike teeth.

Even the staunchest Dart doubters couldn’t overlook this evidence. British anatomist Arthur Keith, who had once called Dart’s assertions “preposterous,” conceded. “I am now convinced,” he wrote in a one-paragraph letter to Nature in 1947, “that Prof. Dart was right and that I was wrong; the Australopithecinae are in or near the line which culminated in the human form.”

A few years later, in 1953, researchers exposed Piltdown Man to be a hoax — someone had planted a modern human skull alongside an orangutan jaw with its teeth filed down. Many experts outside of England had never been convinced by the find in the first place. “It was not a complete surprise when he was proved to be a fake,” Science News Letter reported.

Still, Africa’s role in human evolution was not cemented. From the time of the Taung Child’s unearthing through World War II, discoveries of hominin fossils continued in Indonesia and at a cave site near Beijing called Zhoukoudian. These fossils kept the focus on Asia

.

Olduvai Gorge in Tanzania’s eastern Serengeti Plains was home to a lake millions of years ago. Nearby volcanic eruptions helped preserve fossils at the site and enable dating of the finds.

NOEL FEANS/FLICKR (CC BY 2.0)

A series of surprises

It was ultimately a series of discoveries by the husband-wife paleoanthropologists Louis and Mary Leakey that shifted the focus. Louis, who had grown up in East Africa as the son of English missionaries, had long believed Africa was the human homeland. While Broom was scouring South Africa in the 1930s, the Leakeys began exploring Olduvai Gorge in what is now Tanzania.

Year after year, the pair failed to find hominin fossils. But they dug up stone tools, suggesting that hominins must have lived there. So they kept looking. One day in 1959, while an ill Louis stayed behind in camp, Mary discovered a skull with small canine teeth like Australopithecus. But the fossil’s giant molar teeth, flaring cheekbones and bony crest running along the top of the skull where massive chewing muscles would have attached suggested something else. Nicknamed Nutcracker Man for its chompers, the species was dubbed Zinjanthropus boisei (it’s now called Paranthropus boisei because it is clearly a close cousin of P. robustus, a South African species found by Broom).

Louis and Mary Leakey spent decades digging in East Africa’s Olduvai Gorge (above) before finding hominin fossils. Their luck changed in 1959 when Mary found a skull belonging to an ancient human relative now known as Paranthropus boisei (below).

ACC. 90-105 – SCIENCE SERVICE, RECORDS, 1920S-1970S, SMITHSONIAN INSTITUTION ARCHIVES/FLICKR

Paranthropus boisei

HUMAN ORIGINS PROGRAM, NMNH, SMITHSONIAN INSTITUTION

Until the Zinjanthropus discovery, determining a hominin fossil’s age was largely a guessing game because there was no good way to measure how long ago an ancient fossil had formed. But advances in nuclear physics in the early and mid-20th century led to radioactive dating techniques that allowed age calculations. Using potassium-argon dating, geologists reported in 1961 that Zinjanthropus came from a rock layer about 1.75 million years old. The fossil was three times older than the Leakeys initially suspected. (Later, A. africanus proved to be even older, living about 2 million to 3 million years ago.) The discovery vastly stretched the timescales on which researchers were mapping human evolution.

The surprises didn’t end there. In the early 1960s, the Leakeys’ team recovered fossils of a hominin that lived at roughly the same time as Zinjanthropus but had smaller, more humanlike teeth and a brain notably bigger than that of both Zinjanthropus and Australopithecus. Because of the elevated brain size and details of the hand, the Leakeys argued that this hominin was the one who made the tools at Olduvai Gorge; in 1964, Louis and colleagues placed it in the human genus with the name Homo habilis, or handy man.

The Homo designation was controversial, and to this day paleoanthropologists debate how to classify these fossils. Still, the discoveries at Olduvai Gorge kicked off a paleo-anthropological gold rush in Africa. A 1974 discovery in Ethiopia, for instance, once again expanded the timescale of human evolution. It was one of the most famous discoveries in all of human evolution: the nearly 40 percent complete skeleton of Lucy, known more formally as Australopithecus afarensis, who lived about 3.2 million years ago.

Since then, researchers have shown repeatedly that the hominin fossil record stretches farthest back in Africa. Today, the oldest purported hominins date back some 6 million or 7 million years — to around the time when the ancestors of humans and chimpanzees probably parted ways.

The skeleton known as Lucy, discovered in Ethiopia in 1974, helped confirm that our ancient ancestors evolved upright walking long before big brains.

JOHN KAPPELMAN/UNIV. OF TEXAS AT AUSTIN

On the origin of our species

Even after it became clear that hominins originated in Africa, it was still uncertain where our species, Homo sapiens, began. By the 1980s, paleoanthropologists had largely settled into two camps. One side claimed that, like the earliest hominins, modern humans came from someplace in Africa. The other side championed a more diffuse start across Africa, Asia and Europe.

That same decade saw researchers increasingly relying on genetics to study human origins. Initially, scientists looked to modern people’s DNA to make inferences about ancient populations. But by the late 1990s, geneticists pulled off a feat straight out of science fiction: decoding DNA preserved in hominin fossils.

For paleoanthropologists, studying ancient DNA has been like astronomers getting a new telescope that sees into deep space with a new wavelength of light. It’s revealing things no one even thought to look for, says paleoanthropologist John Hawks of the University of Wisconsin–Madison. “That is the most powerful thing that genetics has handed us.”

And it’s revealed a truly tangled tale.
A trellis or a candelabra

Long before the rise of genetics, or even the discovery of many hominin fossils, unraveling human origins was a quest to explain how the world’s different races came to be. But after the horrors of World War II, anthropologists started to question the validity of race.

“This was a real moral hinge point in the science,” Hawks says. “It was a realization that viewing things through the perspective of race was creating evils in the world.” And it was scientifically dubious, as genetic evidence has shown that people are all so similar that race is more of a cultural concept than a biological phenomenon. Humans, in fact, are less genetically diverse than chimps.

As race was de-emphasized in the 1940s and ’50s, anthropologists started to think more about the mechanisms of evolution and how populations change over time, a direct influence of the “modern synthesis” that had united Darwinian evolution and genetics.

One influential forerunner to this period was anatomist and anthropologist Franz Weidenreich. After leaving Nazi Germany in the 1930s, he ended up in China studying fossils known as Peking Man (now classified as H. erectus), who lived several hundred thousand years ago. Weidenreich noticed that Peking Man shared certain features, such as shovel-shaped incisor teeth, with some present-day East Asians.

From this observation of apparent regional continuity across time, he concluded there had never been just one real-life Garden of Eden. As he wrote in 1947, “Man has evolved in different parts of the old world.”

Rather than picturing a family tree with one main trunk and branches, he envisioned human evolution as a trellis. Vertical lines represented groups of humans from different geographic regions, with the crisscrossing lines of the lattice representing mating between groups. Such gene flow enabled ancient forms across Africa, Asia and Europe to stay a unified species that gradually evolved into modern humans, with some regional variation maintained.

One consequence of all that mixing: “Pure” races never existed.

But a minority of researchers clung to the idea that race was central to understanding human evolution. In 1962, American anthropologist Carleton Coon transformed Weidenreich’s trellis into a candelabra, trimming away the intersecting lines. He argued that modern races stemmed from a common ancestor, but different lines independently evolved into H. sapiens, with races crossing the “sapiens” boundary at different times. In his view, Science News Letter explained, “the Negro race is at least 200,000 years behind the white race on the ladder of evolution.”

It’s a deeply disturbing statement to type today, and it was rejected by many at the time. Coon published his claims during the height of the U.S. civil rights movement, less than a year before Martin Luther King Jr. stood on the steps of the Lincoln Memorial and shared his dream of racial equality. Advocates of segregation cited the supposed evidence of inferiority to justify their racist agenda. But many experts discounted Coon’s views. It’s an “extreme opinion,” one anthropologist told Science News Letter in 1962, lacking “evidence of any nature to support it.”

Still, Coon’s claims tarnished Weidenreich’s view of human evolution. And in the 1960s and ’70s, interest shifted to much earlier stages of hominin history, many millions of years ago.

Homo sapiens arrives, somehow

In the mid-1980s, anthropologists went back to disentangling the roots of H. sapiens. By then, a basic picture had emerged: Hominins arose in Africa, and H. erectus was the first to venture outside of it, by what we now know was nearly 2 million years ago. In some places, H. erectus persisted for a long time; elsewhere, new groups appeared, such as Neandertals (H. neanderthalensis) in Europe and Asia. At some point, somehow, H. sapiens arrived and its predecessors vanished.

T.D. WHITE ET AL/NATURE 2003

Some of the oldest fossils classified as Homo sapiens still lack some features typical of people today. For instance, a roughly 300,000-year-old skull (top) from Jebel Irhoud in Morocco has a relatively long, flat braincase. Only later does a tall, rounded braincase appear to evolve, as seen in a 195,000-year-old skull (middle, white fills in missing pieces) from Omo Kibish and a 160,000-year-old skull (bottom) from Herto, both in Ethiopia.

That “somehow” became a matter of debate in the 1980s, ’90s and into the 2000s.

Milford Wolpoff, a paleoanthropologist at the University of Michigan in Ann Arbor, and colleagues revived the latticework of Weidenreich’s trellis model in the 1980s. Under this “multiregional” view, it was difficult to draw a clean line between the end of H. erectus and the beginning of H. sapiens. In fact, Wolpoff argued that H. erectus and other seemingly distinct groups should be folded into our species. Through intergroup mating these earlier “archaic” H. sapiens gradually evolved the features of “anatomically modern” humans.

Critics doubted there could have been enough intergroup mating back then to allow a small, globally scattered population to remain as one. Chris Stringer, a paleoanthropologist at the Natural History Museum in London, and colleagues proposed instead that H. sapiens originated in just one place — descending from H. erectus or a subsequent species — and then spread across the world. Along the way, these humans replaced other hominins, including Neandertals.

Both theories were difficult to test. For instance, the single-origin idea predicted that the oldest modern human fossils should all be found in just one region. But there weren’t many well-dated fossils from the relevant time period. And seeing ourselves in the fossil record proved challenging. Researchers disagreed on what features defined modern humans. A globular head? A flat face? Something as banal as a chin? These disagreements meant researchers on both sides could often look at the same fossil data and claim support for their position.

Genetic revolution

By the 1980s, DNA offered a new way to investigate the deep past. In 1987, one genetic study shifted momentum toward the single-origin theory, with Africa as the point of origin.

Researchers at the University of California, Berkeley analyzed mitochondrial DNA from people around the world. Because it’s inherited from mother to child and undergoes no genetic reshuffling, mitochondrial DNA preserves a record of maternal ancestry. African populations showed the greatest genetic diversity. And when the team built a family tree using the genetic data, it had two main branches: One held only African lineages and the other contained lineages from all over the world, including Africa. This pattern suggested the “mother” lineage came from Africa. Based on the estimated rate at which mitochondrial DNA accumulates changes, the team calculated that this African Eve lived about 200,000 years ago.

“Thus,” the team reported in Nature, “we propose that Homo erectus in Asia was replaced without much mixing with the invading Homo sapiens from Africa.”

Like fossils, genetic evidence is open to interpretation. Proponents of multiregional evolution pointed out that the African diversity may not be indicative of greater antiquity but simply a sign that African populations were much larger than other ancient groups. Mitochondrial DNA also isn’t a complete record of the past — given its unusual inheritance, lineages are easily lost over time.

Even with those warnings, the “Out of Africa” model gained followers as genetic evidence piled up. And in the late 1980s, 1990s and early 2000s, new dating techniques and discoveries suggested the earliest H. sapiens fossils came from Africa, at sites in Ethiopia dating to between 195,000 and 160,000 years ago. More recently, scientists linked roughly 300,000-year-old Moroccan fossils to H. sapiens.

A new window into the past opened in 1997. A team led by Svante Pääbo, a geneticist now at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, recovered mitochondrial DNA from a Neandertal fossil. It was so different from any modern human’s DNA that it suggested Neandertals must be a separate species. That was another blow to the multiregional model.

But paleoanthropology is like solving a jigsaw puzzle without all the pieces; any new piece can change the picture. That’s what happened in 2010. When Pääbo and colleagues assembled the Neandertal’s genetic blueprint, or genome, and compared it with modern human DNA, the team came to a startling conclusion: About 1 to 4 percent of DNA in non-Africans today came from Neandertals.

“We were naïve to think that humans just marched out of Africa, killed some Neandertals and populated the world,” archaeologist John Shea of Stony Brook University in New York later told Science News.

That genetic data seemed to support a compromise model between Out of Africa and multiregionalism. Yes, modern humans originated in Africa, the idea went, but once they expanded into new territories, they mated with other hominins. Hints of such hybridization had been reported in the late ’90s, when some researchers claimed an ancient skeleton from Portugal had a mix of Neandertal and human features.

Interbreeding wasn’t the only shock to come in 2010. Pääbo’s group also analyzed DNA from a finger bone found at Siberia’s Denisova Cave. Both Neandertals and modern humans had once lived there, but the DNA didn’t match either group. For the first time, genetics had revealed a new hominin. These Denisovans are still mysterious, known from only a few bits of bone and teeth, but they too interbred with humans. For instance, Denisovan DNA accounts for about 2 to 4 percent of Melanesian people’s genome.
It’s complicated

Over the last decade, as genetic and fossil revelations have painted a more complex picture of human origins, paleoanthropologists have moved beyond both the multiregional and simple Out of Africa scenarios. Rather than a tree with separate branches or a trellis, human evolution was probably more like a braided stream, a concept traced to paleoanthropologist Xinzhi Wu of the Chinese Academy of Sciences in Beijing, who used a river metaphor to describe patterns of human evolution in China. Different human populations may have emerged, with some floating away and petering out and others connecting to varying degrees.

One emerging view suggests that much of early human evolution occurred in Africa, but there was not one place on the continent where H. sapiens was born. Starting at least 300,000 years ago, modern H. sapiens features start to show up in the fossil record. But these features didn’t arise all together. Only through the mating of different populations across Africa did the suite of behavioral and biological traits that define us today crystallize, says Eleanor Scerri, an evolutionary archaeologist at the Max Planck Institute for the Science of Human History in Jena, Germany.

“Our origins lie in the interactions of these different populations,” she says. Understanding those interactions is limited by how little of ancient Africa researchers have explored so far. Western, central and much of northern Africa are terra incognita.

There’s still much to explore in other parts of the world too. A single, unifying explanation of human origins may not be possible, as different evolutionary processes probably shaped human history in different regions, says Athreya, of Texas A&M University.

Making more progress on understanding those processes and our roots will come from new discoveries, technological advances and, importantly, new perspectives. For the last 100 years, our origin story has been told by mostly white, mostly male scientists. Welcoming a more diverse group of researchers into paleoanthropology, Athreya says, will reveal blind spots and biases as scientists add to and amend the tale.

This is, after all, everyone’s story.

About Erin Wayman is the magazine managing editor. She has a master’s degree in biological anthropology from the University of California, Davis and a master’s degree in science writing from Johns Hopkins University.

Would we still see ourselves as ‘human’ if other hominin species hadn’t gone extinct?

Would we see Neanderthals (right) as human if they were around today? 

wikipedia, CC BY-SA

October 7, 2021

READER QUESTION: We now know from evolutionary science that humanity has existed in some form or another for around 2 million years or more. Homo sapiens are comparatively new on the block. There were also many other human species, some which we interbred with. The question is then inevitable – when can we claim personhood in the long story of evolution? Are Chimpanzees people? Did Australopithecine have an afterlife? What are the implications for how we think about rights and religion?

 Anthony A. MacIsaac, 26, Paris, France.

In our mythologies, there’s often a singular moment when we became “human”. Eve plucked the fruit of the tree of knowledge and gained awareness of good and evil. Prometheus created men from clay and gave them fire. But in the modern origin story, evolution, there’s no defining moment of creation. Instead, humans emerged gradually, generation by generation, from earlier species.

The creation of Adam by Michelangelo. wikipedia

As with any other complex adaptation – a bird’s wing, a whale’s fluke, our own fingers – our humanity evolved step by step, over millions of years. Mutations appeared in our DNA, spread through the population, and our ancestors slowly became something more like us and, finally, we appeared.

This article is part of Life’s Big Questions
The Conversation’s new series, co-published with BBC Future, seeks to answer our readers’ nagging questions about life, love, death and the universe. We work with professional researchers who have dedicated their lives to uncovering new perspectives on the questions that shape our lives.

Strange apes, but still apes

People are animals, but we’re unlike other animals. We have complex languages that let us articulate and communicate ideas. We’re creative: we make art, music, tools. Our imaginations let us think up worlds that once existed, dream up worlds that might yet exist, and reorder the external world according to those thoughts. Our social lives are complex networks of families, friends and tribes, linked by a sense of responsibility towards each other. We also have awareness of ourselves and our universe: sentience, sapience, consciousness, whatever you call it.

And yet the distinction between ourselves and other animals is, arguably, artificial. Animals are more like humans than we might think – or like to think. Almost all behaviour we once considered unique to ourselves are seen in animals, even if they’re less well developed.

Gorillas use tools too. dean bertoncelj/Shutterstock

That’s especially true of the great apes. Chimps, for example, have simple gestural and verbal communication. They make crude tools, even weapons, and different groups have different suites of tools – distinct cultures. Chimps also have complex social lives and cooperate with each other.

As Darwin noted in Descent of Man, almost everything odd about Homo sapiens – emotion, cognition, language, tools, society – exists, in some primitive form, in other animals. We’re different, but less different than we think.

And in the past, some species were far more like us than other apes – Ardipithecus, Australopithecus, Homo erectus and Neanderthals. Homo sapiens is the only survivor of a once diverse group of humans and human-like apes, the hominins, which includes around 20 known species and probably dozens of unknown species.

The extinction of those other hominins wiped out all the species that were intermediate between ourselves and other apes, creating the impression that some vast, unbridgeable gulf separates us from the rest of life on Earth. But the division would be far less clear if those species still existed. What looks like a bright, sharp dividing line is really an artefact of extinction.

The discovery of these extinct species now blurs that line again and shows how the distance between us and other animals was crossed – gradually, over millennia.
The evolution of humanity

Our lineage probably split from the chimpanzees around 6 million years ago. These first hominins, members of the human line, would barely have seemed human, however. For the first few million years, hominin evolution was slow.

The first big change was walking upright, which let hominins move away from forests into more open grassland and bush. But if they walked like us, nothing else suggests the first hominins were any more human than chimps or gorillas. Ardipithecus, the earliest well-known hominin, had a brain that was slightly smaller than a chimp’s, and there’s no evidence they used tools.

In the next million years, Australopithecus appeared. Australopithecus had a slightly larger brain – larger than a chimp’s, still smaller than a gorilla’s. It made slightly more sophisticated tools than chimps, using sharp stones to butcher animals.

Core from which sharp flakes have been struck off, likely by H. habilis. Olduvai Gorge, Tanzania. 

Nick Longrich, Author provided

Then came Homo habilis. For the first time, hominin brain size exceeded that of other apes. Tools – stone flakes, hammer stones, “choppers” – became much more complex. After that, around 2 million years ago, human evolution accelerated, for reasons we’re yet to understand.
Big brains

At this point, Homo erectus appeared. Erectus was taller, more like us in stature, and had large brains – several times bigger than a chimp’s brain, and up to two-thirds the size of ours. They made sophisticated tools, such as stone handaxes. This was a major technological advance. Handaxes needed skill and planning to create, and you probably had to be taught how to make one. It may have been a meta-tool – used to fashion other tools, such as spears and digging sticks.

Handaxes made by Homo erectus, from Lake Natron, Tanzania. 

Nick Longrich, Author provided

Like us, Homo erectus had small teeth. That suggests a shift from plant-based diets to eating more meat, probably from hunting.

It’s here that our evolution seems to accelerate. The big-brained Erectus soon gave rise to even larger-brained species. These highly intelligent hominins spread through Africa and Eurasia, evolving into Neanderthals, Denisovans, Homo rhodesiensis and archaic Homo sapiens. Technology became far more advanced - stone-tipped spears and firemaking appeared. Objects with no clear functionality, such as jewellery and art, also showed up over the past half-million years.

Some of these species were startlingly like us in their skeletons, and their DNA.

Homo neanderthalensis, the Neanderthals, had brains approaching ours in size, and evolved even larger brains over time until the last Neanderthals had cranial capacities comparable to a modern human’s. They might have thought of themselves, even spoke of themselves, as human.

The Neanderthal archaeological record records uniquely human behaviour, suggesting a mind resembling ours. Neanderthals were skilled, versatile hunters, exploiting everything from rabbits to rhinoceroses and woolly mammoths. They made sophisticated tools, such as throwing spears tipped with stone points. They fashioned jewellery from shells, animal teeth and eagle talons, and made cave art. And Neanderthal ears were, like ours, adapted to hear the subtleties of speech. We know they buried their dead, and probably mourned them.

There’s so much about Neanderthals we don’t know, and never will. But if they were so like us in their skeletons and their behaviour, it’s reasonable to guess they may have been like us in other ways that don’t leave a record - that they sang and danced, that they feared spirits and worshipped gods, that they wondered at the stars, told stories, laughed with friends, and loved their children. To the extent Neanderthals were like us, they must have been capable of acts of great kindness and empathy, but also cruelty, violence and deceit.

Far less is known about other species, like Denisovans, Homo rhodesiensis, and extinct sapiens, but it’s reasonable to guess from their large brains and human-looking skulls that they were also very much like us.
Love and war

I admit this sounds speculative, but for one detail. The DNA of Neanderthals, Denisovans and other hominins is found in us. We met them, and we had children together. That says a lot about how human they were.

It’s not impossible that Homo sapiens took Neanderthal women captive, or vice versa. But for Neanderthal genes to enter our populations, we had to not only mate but successfully raise children, who grew up to raise children of their own. That’s more likely to happen if these pairings resulted from voluntary intermarriage. Mixing of genes also required their hybrid descendants to become accepted into their groups – to be treated as fully human.

These arguments hold not only for the Neanderthals, I’d argue, but for other species we interbred with, including Denisovans, and unknown hominins in Africa. Which isn’t to say that encounters between our species were without prejudice, or entirely peaceful. We were probably responsible for the extinction of these species. But there must have been times we looked past our differences to find a shared humanity.

Finally, it’s telling that while we did replace these other hominins, this took time. Extinction of Neanderthals, Denisovans, and other species took hundreds of thousands of years. If Neanderthals and Denisovans were really just stupid, grunting brutes, lacking language or complex thought, it’s impossible they could have held modern humans off as long as they did.
The human edge

Why, if they were so like us, did we replace them? It’s unclear, which suggests the difference was something that doesn’t leave clear marks in fossils or stone tools. Perhaps a spark of creativity – a way with words, a knack for tools, social skills – gave us an edge. Whatever the difference was, it was subtle, or it wouldn’t have taken us so long to win out.

While we don’t know exactly what these differences were, our distinctive skull shape may offer a clue. Neanderthals had elongated crania, with massive brow ridges. Humans have a bulbous skull, shaped like a soccer ball, and lack brow ridges. Curiously, the peculiar smooth, round head of adult Homo sapiens is seen in young Neanderthals – and even baby apes. Similarly, juvenilised skulls of wild animals are found in domesticated ones, like domestic dogs: an adult dog skull resembles the skull of a wolf pup. These similarities aren’t just superficial. Dogs are behaviourally like young wolves – [less aggressive] and more playful.

Homo heidelbergensis compared with Homo Sapiens. Procy/Shuttertock

My suspicion, mostly a hunch, is that Homo sapiens’ edge might not necessarily be raw intelligence, but differences in attitude. Like dogs, we may retain juvenile behaviours, things like playfulness, openness to meeting new people, lower aggression, more creativity and curiosity. This in turn might have helped us make our societies larger, more complex, collaborative, open and innovative – which then outcompeted theirs.
But what is it?

Until now, I’ve dodged an important question, arguably the most important one. It’s all well and good to discuss how our humanity evolved – but what even is humanity? How can we study and recognise it, without defining it?

People tend to assume that there’s something that makes us fundamentally different from other animals. Most people, for example, would tend to think that it’s okay to sell, cook or eat a cow, but not to do the same to the butcher. This would be, well, inhuman. As a society, we tolerate displaying chimps and gorillas in cages but would be uncomfortable doing this to each other. Similarly, we can go to a shop and buy a puppy or a kitten, but not a baby.

The rules are different for us and them. Even die-hard animal-rights activists advocate animal rights for animals, not human rights. No one is proposing giving apes the right to vote or stand for office. We inherently see ourselves as occupying a different moral and spiritual plane. We might bury our dead pet, but we wouldn’t expect the dog’s ghost to haunt us, or to find the cat waiting in heaven.

And yet, it’s hard to find evidence for this kind of fundamental difference.

The word humanity implies taking care of and having compassion for each other, but that’s arguably a mammalian quality, not a human one. A mother cat cares for her kittens, and a dog loves his master, perhaps more than any human does. Killer whales and elephants form lifelong family bonds. Orcas grieve for their dead calves, and elephants have been seen visiting the remains of their dead companions. Emotional lives and relationships aren’t unique to us.

Perhaps it’s awareness that sets us apart. But dogs and cats certainly seem aware of us - they recognise us as individuals, as we recognise them. They understand us well enough to know how to get us to give them food, or let them out the door – or even when we’ve had a bad day, and need company. If that’s not awareness, what is?

We might point to our large brains as setting us apart, but does that make us human? Bottlenose dolphins have somewhat larger brains than we do. Elephant brains are three times the size of ours; orcas, four times; and sperm whales, five times. Brain size also varies in humans. Albert Einstein had a relatively small brain – smaller than the average Neanderthal, Denisovan, or Homo rhodesiensis – was he less human? Something other than brain size must make us human - or maybe there’s more going on in the minds of other animals, including extinct hominins, than we think.

Are cats aware? Vilvarin/Shutterstock, CC BY-SA

We could define humanity in terms of higher cognitive abilities – art, maths, music, language. This creates a curious problem because humans vary in how well we do all these things. I’m less mathematically inclined than Steven Hawking, less literary than Jane Austen, less inventive than Steve Jobs, less musical than Taylor Swift, less articulate than Martin Luther King. In these respects, am I less human than they are?

If we can’t even define it, how can we really say where it starts, and where it ends – or that we’re unique? Why do we insist on treating other species as inherently inferior, if we’re not exactly sure what makes us, us?

Neither are we necessarily the logical endpoint of human evolution. We were one of many hominin species, and yes, we won out. But it’s possible to imagine another evolutionary course, a different sequence of mutations and historical events leading to Neanderthal archaeologists studying our strange, bubble-like skulls, wondering just how human we were.

The nature of evolution means that living things don’t fit into neat categories. Species gradually change from one into another, and every individual in a species is slightly different – that makes evolutionary change possible. But that makes defining humanity hard.

We’re both unlike other animals due to natural selection, but like them because of shared ancestry; the same, yet different. And we humans are both like and unlike each other – united by common ancestry with other Homo sapiens, different due to evolution and the unique combination of genes we inherit from our families or even other species, such as Neanderthals and Denisovans.

It’s hard to classify living things in strict categories, because evolution constantly changes things, creating diverse species, and diversity within species.

And what diversity it is.

True, in some ways, our species isn’t that diverse. Homo sapiens shows less genetic diversity than your average bacterial strain; our bodies show less variation in shape than sponges, or roses, or oak trees. But in our behaviour, humanity is wildly diverse. We are hunters, farmers, mathematicians, soldiers, explorers, carpenters, criminals, artists. There are so many different ways of being human, so many different aspects to the human condition, and each of us has to define and discover what it means to be human. It is, ironically, this inability to define humanity that is one of our most human characteristics.

Author

Nicholas R. Longrich
Senior Lecturer in Paleontology and Evolutionary Biology, University of Bath