Sunday, September 10, 2023

First cat in space: how a Parisian stray called Félicette was blasted far from Earth


Monkeys and dogs were usually used to test whether humans could survive outside Earth’s atmosphere – but 60 years ago the French tried something a little different



Robin McKie
Sat 9 Sep 2023 

In a few weeks, space scientists will celebrate a remarkable event – the 60th anniversary of the launch of the first cat into space, an astronautical feat that has never been repeated.

A small black-and-white Parisian stray, Félicette, flew on a French rocket on a sub-orbital mission in October 1963 that reached an altitude of 154km, taking her to a place where no feline had gone before – or since.


In the early 60s, dogs and monkeys were the animals usually used by scientists to find out exactly how dangerous conditions were in outer space and to assess if humans could survive trips beyond the edge of Earth’s atmosphere. Russia preferred dogs, the US generally chose monkeys.

But France decided to be different. A total of 14 stray cats were gathered by staff at France’s space agency Cerma – Centre d’Enseignement et de Recherches de Médecine Aéronautique – for selection as feline astronauts, though the cats were deliberately not given names in order to prevent scientists from becoming too fond of them. The cat selected to travel to space was simply known as C341.

Then, after news was announced of its flight on a Veronique rocket on 18 October 1963 and subsequent safe return to Earth, the French press decided this feline trailblazer had to have a name. They picked Felix after the cartoon cat character, only to discover that C341 was female. Her name was adjusted to Félicette, as a result.
Félicette, pictured with the French space team after her return to earth. 
Photograph: Matthew Guy

In putting Félicette in one of its rockets, France added a new species to the list of creatures that scientists had already hurled into space, a roll-call that has since been swelled over subsequent decades by the addition of some very unlikely animal astronauts.

Tortoises have been put in orbit round the moon; thousands of jellyfish were once flown on a space shuttle; and in 1973, two garden spiders, Anita and Arabella, were taken to the Skylab orbiting laboratory to see if they could spin webs in microgravity. (They could but the webs were unevenly shaped, scientists found.)

“In the 60s, scientists and engineers were primarily concerned about how dangerous it might be for a human to be in a capsule in outer space, and most animal space flights were undertaken to see if they suffered or their lives were threatened by the weightlessness or increased radiation or other effects they might experience up there,” said astronomer Jake Foster at the Royal Observatory Greenwich.

“The fact that they did not succumb paved the way for humans to begin journeys into space.”

In fact, the blasting of animals into space has a surprisingly long pedigree, going back to the late 1940s when US scientists selected a very humble lifeform to be the first creatures to soar beyond our atmosphere. They chose fruit flies.

A payload of Drosophila melanogaster was loaded into a V-2 rocket, recovered from Nazi Germany’s missile programme, and fired to a height of 109km. The capsule was then parachuted back down to New Mexico and the flies were studied to assess how they had been affected by cosmic radiation.

This flight was followed in the US by a series of other sub-orbital missions that carried monkeys above the atmosphere before their craft arced back to Earth.

Many died in the process, either of suffocation or when their capsule suffered parachute failure.

However, it was the Soviet dog Laika who made world headlines for her sacrificial role as an animal astronaut. A stray mongrel picked from the streets of Moscow, she flew aboard Sputnik 2 on 3 November 1957. This was only the second satellite ever put into orbit round Earth, and the Soviet Union decided to maximise its headline potential by using it to carry a living creature.

Laika died of overheating on the craft’s fourth orbit. No one had expected her to live. The technology for de-orbiting spacecraft had not yet been developed and she was destined to die in space.

Ham, the first chimpanzee in space, prepares for his first flight in Mercury Redstone-2 (Mr-2), part of Nasa’s Mercury programme in the 1960s. 
Photograph: Encyclopaedia Britannica/Universal Images Group/Getty Images

At the time, most media coverage of her journey focused on its implications for the US-Soviet space race and the cold war. Nevertheless, there was criticism of the mission, with the UK National Canine Defence League calling on all dog owners to observe a minute’s silence on each day that Laika remained in space.


Later missions were designed to bring animals safely back to Earth after their flights. Some were successful, some not. In July 1960, dogs Lisichka and Bars died when their Soviet launcher exploded shortly after lift-off.

However, this mission was followed by the successful launch and safe retrieval of a capsule carrying dogs Belka and Strelka later that year. According to Animals in Space by Colin Burgess and Chris Dubbs, the Soviet Union launched dogs on rockets 71 times between 1951 and 1966, with 17 deaths.

Today, rules governing the use of animals in space experiments are much stricter, added Foster. “Animals are also being put into orbit for different reasons. Modern missions are less concerned about testing the dangers of space and focus more on researching the long-term effects of living in space. That, in turn, reflects an interest in developing long-term missions such as trips to Mars.”

In addition, scientists study various lifeforms in orbit – mainly on the International Space Station – to unravel the influence that gravity has on living organisms on Earth. In orbit, gravity’s pull is very much lighter than on Earth, and this can shed light on how the growth of animals and plants proceeds.
A tortoise inches closer to the space shuttle Discovery at the Kennedy Space Center in 2006.
 Photograph: Rick Wilking/REUTERS

“Plants develop differently in microgravity,” said Nasa scientist Jennifer Buchli. “They don’t know which way is down any more. They no longer have a gravity signal for their root structure. So we examine their RNA to see how it’s giving directions and signals, and how that differs from the way plants behave on Earth.”

Another ISS project, highlighted by Foster, involved mice that spent 90 days there as part of a study to see how sleep schedules and guts respond to being in space for so long. “They had mice up in space and a control group on Earth to compare results.”

Perhaps the most astonishing act of space survival was demonstrated by the water bear, or tardigrade, a microscopic invertebrate that can tolerate the hottest and coldest environments on Earth, and can survive decades without water.

In an intriguingly titled experiment called Tardis (Tardigrades in Space), a European research team sent 3,000 of these little creatures into orbit, where they spent 12 days on the outside of a rocket. Remarkably, 68% of them survived the cold, zero gravity, vacuum and radiation. “The water bears are something new. Nobody knew about that capability,” said René Demets, a European Space Agency project biologist.

Rocketman’s best friend … Laika became the first canine in space when she flew aboard Sputnik 2 on 3 November 1957.
 Photograph: Science History Images/Alamy

Being flown into space is no longer a death sentence, scientists insist. Félicette was not so lucky, however. She lived through her flight and survived her return to Earth with her cone-shaped capsule landing in a position that left her hanging upside down with her bottom sticking up in the air until she was retrieved.


Worse was to follow. Two months after her trip into space, Félicette was put down so that scientists could study her body to determine if she had suffered any anatomical or physiological damage. They later concluded that they had learned nothing of any use from the autopsy. No more cats were put into space, and France never launched its own astronauts.

However, Félicette is still remembered. A statue of her, sitting on a globe gazing upwards, was erected at the International Space University at Strasbourg in 2019.



Enbridge Gas Caught Lying About its Home Heating Costs and Impacts


September 07, 2023
Keith Brooks
Programs Director

In an attempt to expand its “natural” gas infrastructure across Ontario, Enbridge Gas is telling residents that gas is the cheapest way to heat their homes. It’s not.

So we’re calling them out.

Today, we filed a complaint with the Competition Bureau over Enbridge Gas’ deceptive marketing.

The company is falsely claiming that “natural” gas, better described as fossil gas, is the most cost-effective way for people to heat their homes, when in reality electric heat pumps are a significantly cheaper option. The deceptive marketing is directed to customers in communities that Enbridge has recently connected to its gas pipeline network or is planning to connect in the near future.
Natural Gas vs Electric

For a long time, fossil gas was the cheapest way to heat buildings. It’s the reason why so many homes are hooked up to the “natural” gas system. But now, electric heat pumps are a much cheaper option.



Due to their high efficiency – three to five times higher than gas – annual energy costs for heat pumps are much lower. Upfront equipment costs can also be lower because heat pumps provide both heating and cooling in one unit and they qualify for a number of government rebate programs.

Despite what Enbridge’s marketing materials are saying, a typical resident recently connected to Enbridge’s fossil gas system could save over $10,000 if they install an electric heat pump (over the lifetime of the equipment) rather than connecting to fossil gas.

What’s more, switching to heat pumps would reduce a home’s carbon emissions for space heating, cooling, and water heating significantly.

But Enbridge Gas does not want you to know that.
What is “Natural” gas, really?

Don’t let the oil and gas industry’s branding of fossil fuel as “natural” gas fool you into thinking it’s clean and green. Fossil gas is a potent greenhouse gas that pollutes the air and causes climate change.



Heating our homes and businesses with fossil gas is responsible for 19 per cent of Ontario’s greenhouse gas emissions.

It’s clear that we need to transition to electric heating if we are to have a chance at meeting our emissions reductions targets.

But Enbridge is making this very difficult.
What does Enbridge Gas have at stake?

Enbridge Gas owns nearly all of the fossil gas distribution pipelines in Ontario. And it serves over 99.7% of all gas customers in the province. So it has a lot to lose, and gain:As a for-profit company, it has a clear profit motive to encourage Ontarians to switch to gas and stay with gas for their homes and businesses.
It has a strong financial interest in gaining and keeping customers because they are the ones that pay for its existing and new pipelines. Those gas distribution charges on your monthly bill? They pay for Enbridge pipelines!
A big threat to Enbridge’s expansion plans is that customers using oil heating decide to switch to electric heat pumps instead of gas.

No wonder Enbridge is advertising so aggressively.
Enbridge Gas’ false advertising

Enbridge marketing materials state that customers will save money by switching to gas. Their advertising says “When compared to using electricity, propane or oil, switching to natural gas could save you up to 54%* per year on home and water heating costs.” But this is blatantly false. Switching to an electric heat pump would be significantly less expensive.



Enbridge’s marketing materials also use deceptive wording about the impact of fossil gas, describing it as “low carbon” and “clean energy.” They leave the general impression that switching to gas is environmentally conscious, which is not true. Switching from propane or oil to gas may result in lower carbon emissions. But switching from electricity to gas will result in higher carbon emissions. And heating with heat pumps results in the lowest carbon emissions.

What needs to happen

The Competition Bureau needs to stop Enbridge from its false advertising.

With each week that passes, more customers sign up to convert their heating to gas instead of purchasing a high-efficiency electric heat pump. Each time this happens, unnecessarily high energy costs and carbon pollution are effectively locked in for a decade or more to the detriment of consumers and the climate.

You can add your voice by sharing your anger on twitter.

And if you’re curious about how to make the switch to an electric heat pump, check out our website for more information on the various Federal rebates, loans, and programs that can help you.

For now, let’s make sure Enbridge is forced to stop lying to people.

 

ONTARIO

Update in ongoing labour negotiations with Hastings Prince Edward Public Health

Belleville, ON, Canada / Quinte News
Update in ongoing labour negotiations with Hastings Prince Edward Public Health

Striking Hastings Prince Edward Public Health nurses on the picket line, August 21, 2023. (Photo: Alana Cameron/Quinte News)

The following was sent by the Hastings Prince Edward Public Health Unit

Hastings Prince Edward Public Health (HPEPH) is currently in the process of negotiations with unionized staff represented by Canadian Union of Public Employees (CUPE) local 3314. HPEPH is open to continuing negotiations, however as CUPE will be in a legal strike position on September 22, 2023, HPEPH is preparing for the possibility of work stoppage.

As HPEPH staff represented by Ontario Nurses’ Association Local 31 (ONA) continue to exercise their legal right to strike, several services offered by HPEPH have been temporarily disrupted since mid-August. We appreciate the patience of the public throughout this service disruption.

While HPEPH is optimistic that an agreement will be reached with both parties, with the continued ONA work stoppage and in preparation for a potential work stoppage of CUPE staff, some HPEPH programs, clinics, and classes are being proactively cancelled to avoid last minute notification to clients. HPEPH’s service disruption notice has been updated to reflect these cancellations.

If an agreement is not reached with CUPE and/or ONA, HPEPH services will be temporarily limited to core public health services critical to protect public safety. Our service disruption notice will be updated accordingly.

The health and wellbeing of our community is our top priority and, as has been shared over the past few weeks, plans are in place to address the disruption in services. The patience and understanding of the community are appreciated as we work to maintain core public health services and continue efforts to resolve the current labour disruption fairly and responsibly.

If you are coming to the HPEPH offices, here are a few things to keep in mind regarding the picket line:

  • In the event of a work stoppage by both CUPE and ONA, public access to HPEPH offices will be limited.
  • Picketers can’t stop visitors and clients from entering the property, although some delays should be expected.
  • Picketing is a legal activity. Please be respectful of the picketers.
  • Picketers are allowed to communicate information to the individuals entering the property (eg. hand out flyers).
  • Picketing should not include threats, intimidation, or aggressive behaviour.
  • Picketing should not impede traffic or cause road safety issues.
  • Do not force your way through the picket line but wait until the path is open and proceed carefully. Pedestrians always have the right of way.

ALBERTA

Braid: Old-fashioned government incompetence wrecked a working lab-test system

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What a mess. The DynaLife lab testing fiasco stands as one of the worst Alberta government blunders in many years.

It was driven by political pressures, AHS imperialism, a rushed contract that never should have been signed and costs yet to be revealed.

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On Aug. 18, the UCP government and DynaLife parted ways after wait times for blood and other tests ran out of control in Calgary.

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DynaLife had done reliable lab testing in Edmonton and the north for many years. Suddenly it lost the whole province, not just the troubled south.

It’s not clear if DynaLife voluntarily decided to quit Alberta, or if the UCP pushed the company out. Lawsuits may yet emerge from this.

The government has provided no details of the original contract that disastrously extended private testing, or the cost of ending the agreement.

The NDP has asked provincial auditor general Doug Wylie to investigate. The auditor’s office says no decision has been made yet. If any current problem deserves urgent inquiry and disclosure, this is surely it.

New Health Minister Adriana LaGrange looked deeply uncomfortable on the August Friday afternoon as she tried to paint this move as an improvement in health care.

The truth is that the government, already facing so many health-care pressures in hospitals, family medicine and surgeries, virtually wrecked a public testing system that was working very well.

After the southern shift took formal effect on Feb. 23, wait times began growing in Calgary. They soon stretched to weeks for an online appointment, and then to months.

Clinics were swamped by walk-ins. People with appointments they booked far ahead often had to wait hours after they arrived at a clinic.

Danielle Smith
Alberta Premier Danielle Smith speaks at a press conference in McDougall Centre in Calgary on Monday, Aug. 14. PHOTO BY AZIN GHAFFARI /Postmedia

Doctors were alarmed. Many had patients with serious conditions that needed prompt diagnosis.

Lab technicians, who had no part in causing this, came under intense pressure and occasional abuse.

And it was all unnecessary. Testing under Alberta Precision Laboratories (APL) had been one area that seemed to work reliably in the south. DynaLife was still doing fine in Edmonton.

In near panic, the government threw resources at the problem, or said it did, shifting some community testing to the remaining APL labs in hospitals and urgent-care centres.

None of that had much effect. Then came the dramatic August cancellation that’s supposed to bring improvement.

It hasn’t — at least, not yet. The booking website (albertaprecisionlabs.ca) shows that wait times might have improved slightly, but can still be very long.

Edmonton, meanwhile, is still fairly well served.

Even in government, people were shocked at the dramatic move to end all dealings with DynaLife.

The new contract had been announced late last year — after Premier Danielle Smith took office — and painted in February as a money-saving move that would be more efficient.

People close to the matter say the original contract had to be deeply flawed. One obvious problem was that lab technicians, suddenly in the private sector, took a drop in pay. This was sure to cause trouble.

Dynalife might have expected adjustments to get funding for problems that arose.

But a new regime was in place. Smith’s crew may have taken a tougher attitude to the contract and resisted pressure for new funding.

Jason Copping, the health minister who announced the change, lost in the May 29 election. So did Tyler Shandro, the former minister who was involved earlier.

DynaLife lab tour
Former Alberta minister of health Jason Copping, centre, tours Alberta Precision Laboratories in Calgary with Dr. Dylan Pillai, South Sector Medical Director, Alberta Precision Laboratories, right and Jason Pincock, president and CEO, DynaLIFE Medical Labs on Thursday, June 2, 2022. Gavin Young/Postmedia

Jason Kenney, premier at the time the drive began, was long gone.

Another player was AHS, many of whose executives were against private community testing, and still are. They want a provincewide public system. Now they have it, in the most bizarre circumstances.

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Smith says all this took shape before she took office. But she was premier for ore than three months before the system kicked in.

A bad deal could and should have been killed before it saw the light of day. There’s plenty of blame to go around here.

AHS seems to be the winner in the background tussle for a public provincial system, but that may only be temporary.

There’s talk that the UCP will at some point move once again toward provincewide private lab testing.

Many people will blame privatization for this debacle, but the main villain seems to be old-fashioned incompetence.

Don Braid’s column appears regularly in the Herald.

Regulator yanks thousands of wells from troubled oil company, transfers for cleanup

OIL COMPANY LOSES WELLS

Alberta's energy regulator has transferred thousands of oil and gas wells and other facilities held by a troubled Calgary company to the group that's responsible for cleaning up poorly maintained or abandoned sites.

In an order issued Monday, the regulator has told AlphaBow Energy that it is no longer allowed on the sites it owns and has transferred control to the Orphan Well Association.

Regulatory documents show more than 3,000 wells, 2,700 pipeline segments and 350 facilities are affected.

Those documents suggest that AlphaBow's environmental liability totals $154 million.

Lars DePauw of the Orphan Well Association says staff are visiting the sites to determine what work needs to be done to ensure they are safe.

Documents issued by the regulator detail a long list of problems, with fewer than half of field checks on the company rated satisfactory.

Evolution of Vertebrate Armor: How Fish Evolved Their Protective Bony Scales

Sterlet Sturgeon Dorsal Scutes

Dorsal scutes of sterlet sturgeon. A recent study discovered that a specific type of stem cell, the trunk neural crest cell, is responsible for the development of bony protective scales (scutes) in fish. This breakthrough reveals how our soft-bodied evolutionary ancestors developed protective armor, paving the way for the evolution of a multitude of vertebrate species. Credit: Courtesy of J. Stundl

A Caltech study identified trunk neural crest cells as the origin of protective bony scales in fish, shedding light on the evolution of vertebrate armor.

About 350 million years ago, your evolutionary ancestors—and the ancestors of all modern vertebrates—were merely soft-bodied animals living in the oceans. In order to survive and evolve to become what we are today, these animals needed to gain some protection and advantage over the ocean’s predators, which were then dominated by crustaceans.

The evolution of dermal armor, like the sharp spines found on an armored catfish or the bony diamond-shaped scales, called scutes, covering a sturgeon, was a successful strategy. Thousands of species of fish utilized varying patterns of dermal armor, composed of bone and/or a substance called dentine, an important component of modern human teeth. Protective coatings like these helped vertebrates survive and evolve further into new animals and ultimately humans.

But where did this armor come from? How did our ancient underwater ancestors evolve to grow this protective coat?

Now, using sturgeon fish, a new study finds that a specific population of stem cells, called trunk neural crest cells, are responsible for the development of bony scutes in fish. The work was conducted by Jan Stundl, now a Marie Sklodowska-Curie postdoctoral scholar in the laboratory of Marianne Bronner, the Edward B. Lewis Professor of Biology and director of the Beckman Institute at Caltech. A paper describing the research was published recently in the journal Proceedings of the National Academy of Sciences (PNAS).

Jan Stundl

Jan Stundl holds a sturgeon fish in the laboratory. Credit: Courtesy of J. Stund

The Bronner laboratory has long been interested in studying neural crest cells. Found in all vertebrates including fish, chickens, and ourselves, these cells become specialized based on whether they arise from the head (cranial) or spinal cord (trunk) regions. Both cranial and trunk neural crest cells migrate from their starting points throughout the animal’s developing body, giving rise to the cells that make up the jaws, heart, and other important structures. After a 2017 study from the University of Cambridge showed that trunk neural crest cells give rise to dentine-based dermal armor in a type of fish called the little skate, Stundl and his colleagues hypothesized that the same population of cells might also give rise to bone-based armor in vertebrates broadly.

Single Sturgeon Scute

A reconstruction of a single sturgeon scute, close up. Bone-forming cells are marked in magenta. Credit: Courtesy of J. Stundl

To study this, Stundl and the team turned to the sturgeon fish, specifically the sterlet sturgeon (Acipenser ruthenus). Modern sturgeons, best known for their production of the world’s most expensive caviar, still have many of the same characteristics as their ancestors from millions of years ago. This makes them prime candidates for evolutionary studies.

Using sturgeon embryos grown at the Research Institute of Fish Culture and Hydrobiology in the Czech Republic, Stundl and his team used fluorescent dye to track how the fish’s trunk neural crest cells migrated throughout its developing body. Sturgeons begin to develop their bony scutes after a couple of weeks, so the researchers kept the growing fish in a darkened lab in order to not disturb the fluorescent dye with light.

The team found fluorescently labeled trunk neural crest cells in the exact locations where the sturgeon’s bony scutes were forming. They then used a different technique to highlight the fish’s osteoblasts, a type of cell that forms bone. Genetic signatures associated with osteoblast differentiation were found in the fluorescent cells in the fish’s developing scutes, providing strong evidence that the trunk neural crest cells do in fact give rise to bone-forming cells. Combined with the 2017 findings about neural crest cells’ role in forming dentine-based armor, the work shows that trunk neural crest cells are indeed responsible for giving rise to the bony dermal armor that enabled the evolutionary success of vertebrate fish.

“Working with non-model organisms is tricky; the tools that exist in standard lab organisms like mouse or zebrafish either do not work or need to be significantly adapted,” says Stundl. “Despite these challenges, information from non-model organisms like sturgeon allows us to answer fundamental evolutionary developmental biology questions in a rigorous manner.”

“By studying many animals on the Tree of Life, we can infer what evolutionary events have taken place,” says Bronner. “This is particularly powerful if we can approach evolutionary questions from a developmental biology perspective, since many changes that led to diverse cell types occurred via small alterations in embryonic development. We were very fortunate to receive funding from Caltech’s Center for Evolutionary Sciences, which helped us make studies of this sort possible.”

Caltech’s Center for Evolutionary Science (CES) is an Institute-wide, multi-division organization that recognizes and supports the investigation of evolutionary change in the natural world via both biotic and anthropogenic forces.

“Evolution is a central theme that runs through all of biology; it unifies our discipline,” says Joe Parker, Assistant Professor of Biology and Biological Engineering, Chen Scholar, and co-director of the CES. “Caltech is an incredible place with so many groups pursuing evolutionary problems in different contexts, including at the interface of evolution and development biology—as this study so beautifully shows.”

The paper is titled “Ancient vertebrate dermal armor evolved from trunk neural crest” by Jan Stundl, Megan L. Martik, Donglei Chen, Desingu Ayyappa Raja, Roman Franěk, Anna Pospisilova, Martin Pšenička, Brian D. Metscher, Ingo Braasch, Tatjana Haitina, Robert Cerny, Per E. Ahlberg and Marianne E. Bronner, 17 July 2023, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2221120120

In addition to Bronner and Stundl, Caltech co-authors are former postdoctoral scholar Megan Martik, now at the University of California Berkeley, and postdoctoral scholar Desingu Ayyappa Raja. Additional co-authors are Donglei Chen, Tatjana Haitina, and Per Ahlberg of Uppsala University in Uppsala, Sweden; Roman Franěk and Martin Pšenička of the University of South Bohemia in the Czech Republic; Anna Pospisilova and Robert Cerny of Charles University in Prague, Czech Republic; Brian Metscher of the University of Vienna in Austria; and Ingo Braasch of Michigan State University. Funding was provided by the European Union’s Horizon 2020 research and innovation program; the National Institutes of Health; a Wallenberg Scholarship from the Knut & Alice Wallenberg Foundation; the Helen Hay Whitney Foundation; the Ministry of Education, Youth and Sports of the Czech Republic; the Czech Science Foundation; and the National Science Foundation.

Bronner and Parker are affiliated faculty members with the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech.

It’s reassuring to think humans are evolution’s ultimate destination – but research shows we may be an accident

The Cambrian explosion, about 530 million years ago, was when most of the major groups of animals first appear in the fossil record. 

THE CONVERSATION
Published: September 5, 2023 
dia CommonsDepending upon how you do the counting, there are around 9 million species on Earth, from the simplest single-celled organisms to humans.

It’s reassuring to imagine that complex bodies and brains like ours are the inevitable consequence of evolution, as if evolution had a goal. Unfortunately for human egos, a recent study comparing over a thousand mammals – the group we belong to – painted a less gratifying picture.

Evolutionary biologists in the late 18th century, including Jean-Baptiste Lamarck, reasoned that life must have an innate tendency to evolve into ever more complex forms, and

believed this reflected God’s design. However, by the mid-19th century, Charles Darwin showed that natural selection has no direction, and will sometimes make organisms simpler.

Modern biologists agree that the most complex organisms have become more complex over the last 4 billion years, but they disagree about what sort of process accounts for this.

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Because most organisms are still very simple, one possibility is that maximum complexity has increased “accidentally”, like the diffusion of a drop of ink in a glass of water. If true, this could be a blow to our human sense of significance as the most complex organisms.

Another theory is that increasing complexity is driven, on average, by natural selection. Sometimes selection acts on many, independent branches of the tree of life in a similar way and in parallel. This can produce similar effects in many of those branches and is known as a driven trend.

While driven trends need not imply divine purpose, they at least suggest that complexity was mostly an improvement, which is reassuring for us humans.

So which pattern is the most common in the evolution of complexity: accidental diffusion or driven trend?

Most changes and mutations are bad, and these variants are usually weeded out through a process called stabilising selection, which acts to maintain the status quo. But if most mutations make things function less well, doesn’t this make it very difficult for evolutionary novelties to arise?

In fact, evolution often operates on multiple copies of things. For example, a single gene might be duplicated within the same organism.

Provided one copy maintains its original function, the other copy can accumulate mutations without putting its bearer at an immediate disadvantage. These mutated copies are usually edited out over time, but occasionally they acquire a new function that gives an advantage.

Even more remarkably, whole genomes – every single gene in an organism – can be duplicated in one generation. Under these circumstances, there are many chances that copies of some genes will acquire a new function.

For example, sturgeons and paddle fishes underwent a whole genome duplication 250 million years ago, and this may explain how they survived the biggest ever mass extinction that wiped out 96% of other marine species.


Millipedes have lots of pairs of legs that are essentially identical. Shrimps have fewer pairs of legs but with many different functions. 
photochem_PA/Alexander Semenov, CC BY-NC-SA

Identical copies of structures such as segments and limbs can also be made via duplication processes. For example, millipedes have lots of legs, but they are the same design copied lots of times.

Shrimps, by contrast have many different types of legs modified for feeding, walking, swimming and brooding eggs. A biological principle called the zero force evolutionary law states that these copies will tend to become less similar by accidental diffusion alone, unless stabilising selection acts to keep the status quo. Of course, natural selection may also act to make the copies less similar if this has an advantage.

Our paper shows that increasing complexity in mammals has both diffusive and driven aspects. Rather than marching towards greater complexity, mammals evolved in lots of different directions, with only some lineages pushing the upper bounds of complexity.


The spine of the domestic cat has several different types of vertebrae doing different jobs.
Kirill Tsukanov/Wikimedia, CC BY-SA

Surely nature selects for complexity just a bit?

Unfortunately, there is little research addressing this question. One of the few published studies demonstrates that crustaceans (crabs, lobsters, shrimps and their relatives) evolved with a driven trend for increasing complexity over the last half a billion years.

Like crustaceans, and all vertebrates, we have bodies made of repeating blocks of tissue (called somites). These are most visible in our vertebral column (or spine) and ribs, and in the six-pack of a lean athlete. Across mammals, the number of vertebrae (the bones that make up the spine) varies and they are shaped to do different jobs in the neck, thorax, back, sacrum and tail.

Counting the number of bones in different regions can quantify one aspect of complexity across all mammals. In our study sampling over a thousand mammal species, many groups – including whales, bats, rodents, carnivores and, our own group, the primates – independently evolved complex vertebral columns. This suggests higher complexity can be a winning formula, and that selection is driving this in multiple branches of the mammal tree.

However, many other branches have a low plateau in complexity or even become simpler. Elephants, rhinos, sloths, manatees, armadillos, golden moles and platypuses all thrived despite the fact they have relatively simple vertebral columns. The direction of evolution all depends on context.

 
In a study of 1,136 mammal species, we find a driven trend for increasing complexity in multiple parallel lineages. Left hand panel is the number of vertebrae. Right hand panel is our index of complexity. Blue lines are lower values, while red lines are higher values. Li et al; Nature Ecology & Evolution (2023), CC BY-ND

Research into the evolution of complexity has only recently started gathering pace, so there is much we still don’t know. But we do know that the story of mammalian evolution hasn’t been a directional “march of progress”, but rather has many characteristics of a random and diffusive walk.

Authors
Matthew Wills
Professor of Evolutionary Palaeobiology at the Milner Centre for Evolution, University of Bath
Marcello Ruta
Senior Lecturer, Life Sciences, University of Lincoln


Disclosure statement

Matthew Wills receives funding from BBSRC, NERC, The Leverhulme Trust and The John Templeton Foundation

Marcello Ruta receives funding from the John Templeton Foundation
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