Do we need a new theory of evolution?

Yeah, that place out 'there'. Anything not really Cambodia related should go here.
down_time
Expatriate
Posts: 205
Joined: Sun Nov 28, 2021 5:54 pm
Reputation: 174
Great Britain

Do we need a new theory of evolution?

Post by down_time »

Image

A new wave of scientists argues that mainstream evolutionary theory needs an urgent overhaul. Their opponents have dismissed them as misguided careerists – and the conflict may determine the future of biology
Strange as it sounds, scientists still do not know the answers to some of the most basic questions about how life on Earth evolved. Take eyes, for instance. Where do they come from, exactly? The usual explanation of how we got these stupendously complex organs rests upon the theory of natural selection...
...the basic story of evolution, as recounted in countless textbooks and pop-science bestsellers [is] according to a growing number of scientists, absurdly crude and misleading.
“If we cannot explain things with the tools we have right now,” the Yale University biologist Günter Wagner told me, “we must find new ways of explaining.”

In 2014, eight scientists took up this challenge, publishing an article in the leading journal Nature that asked “Does evolutionary theory need a rethink?” Their answer was: “Yes, urgently.” Each of the authors came from cutting-edge scientific subfields, from the study of the way organisms alter their environment in order to reduce the normal pressure of natural selection – think of beavers building dams – to new research showing that chemical modifications added to DNA during our lifetimes can be passed on to our offspring. The authors called for a new understanding of evolution that could make room for such discoveries. The name they gave this new framework was rather bland – the Extended Evolutionary Synthesis (EES) – but their proposals were, to many fellow scientists, incendiary....
...discoveries, which began in the late 60s, came from molecular biologists. While the modern synthesists looked at life as if through a telescope, studying the development of huge populations over immense chunks of time, the molecular biologists looked through a microscope, focusing on individual molecules. And when they looked, they found that natural selection was not the all-powerful force that many had assumed it to be.

They found that the molecules in our cells – and thus the sequences of the genes behind them – were mutating at a very high rate. This was unexpected, but not necessarily a threat to mainstream evolutionary theory. According to the modern synthesis, even if mutations turned out to be common, natural selection would, over time, still be the primary cause of change, preserving the useful mutations and junking the useless ones. But that isn’t what was happening. The genes were changing – that is, evolving – but natural selection wasn’t playing a part. Some genetic changes were being preserved for no reason apart from pure chance. Natural selection seemed to be asleep at the wheel...
...Where once Christians had complained that Darwin’s theory made life meaningless, now Darwinists levelled the same complaint at scientists who contradicted Darwin...
Image
A spadefoot toad catching a dragonfly. Photograph: Buddy Mays/Getty Images

Other assaults on evolutionary orthodoxy followed. The influential palaeontologists Stephen Jay Gould and Niles Eldredge argued that the fossil record showed evolution often happened in short, concentrated bursts; it didn’t have to be slow and gradual. Other biologists simply found that the modern synthesis had little relevance to their work. As the study of life increased in complexity, a theory based on which genes were selected in various environments started to seem beside the point. It didn’t help answer questions such as how life emerged from the seas, or how complex organs, such as the placenta, developed.
The case for EES rests on a simple claim: in the past few decades, we have learned many remarkable things about the natural world – and these things should be given space in biology’s core theory. One of the most fascinating recent areas of research is known as plasticity, which has shown that some organisms have the potential to adapt more rapidly and more radically than was once thought. Descriptions of plasticity are startling, bringing to mind the kinds of wild transformations you might expect to find in comic books and science fiction movies.

Image
The Senegal bichir. Photograph: blickwinkel/Alamy

Emily Standen is a scientist at the University of Ottawa, who studies Polypterus senegalus, AKA the Senegal bichir, a fish that not only has gills but also primitive lungs. Regular polypterus can breathe air at the surface, but they are “much more content” living underwater, she says. But when Standen took Polypterus that had spent their first few weeks of life in water, and subsequently raised them on land, their bodies began to change immediately. The bones in their fins elongated and became sharper, able to pull them along dry land with the help of wider joint sockets and larger muscles. Their necks softened. Their primordial lungs expanded and their other organs shifted to accommodate them. Their entire appearance transformed. “They resembled the transition species you see in the fossil record, partway between sea and land,” Standen told me. According to the traditional theory of evolution, this kind of change takes millions of years. But, says Armin Moczek, an extended synthesis proponent, the Senegal bichir “is adapting to land in a single generation”. He sounded almost proud of the fish.

Moczek’s own area of expertise is dung beetles, another remarkably plastic species. In a cold environment, dung beetles will grow larger wings to range further for food; in a warm one, a rounder body and stomach to gorge locally. The crucial thing about these observations, which challenge the traditional understanding of evolution, is that these sudden developments all come from the same underlying genes. The species’s genes aren’t being slowly honed, generation by generation. Rather, during its early development it has the potential to grow in a variety of ways, allowing it to survive in different situations.

“We believe this is ubiquitous across species,” says David Pfennig of the University of North Carolina at Chapel Hill. He works on spadefoot toads, amphibians the size of a Matchbox car. Spadefoots are normally omnivorous, but spadefoot tadpoles raised solely on meat grow larger teeth, more powerful jaws, and a hardy, more complex gut. Suddenly, they resemble a powerful carnivore, feeding on hardy crustaceans, and even other tadpoles.
Biology is full of theories like this. Other interests of the EES include extra-genetic inheritance, known as epigenetics. This is the idea that something – say a psychological injury, or a disease – experienced by a parent attaches small chemical molecules to their DNA that are repeated in their children. This has been shown to happen in some animals across multiple generations, and caused controversy when it was suggested as an explanation for intergenerational trauma in humans. Other EES proponents track the inheritance of things like culture – as when groups of dolphins develop and then teach each other new hunting techniques – or the communities of helpful microbes in animal guts or plant roots, which are tended to and passed on through generations like a tool. In both cases, researchers contend that these factors might impact evolution enough to warrant a more central role. Some of these ideas have become briefly fashionable, but remain disputed. Others have sat around for decades, offering their insights to a small audience of specialists and no one else. Just like at the turn of the 20th century, the field is split into hundreds of sub-fields, each barely aware of the rest.
The current superstar of this view, known as neutral evolution, is Michael Lynch, a geneticist at the University of Arizona. Lynch is soft-spoken in conversation, but unusually pugnacious in what scientists call “the literature”. His books rail against scientists who accept the status quo and fail to appreciate the rigorous mathematics that undergirds his work. “For the vast majority of biologists, evolution is nothing more than natural selection,” he wrote in 2007. “This blind acceptance […] has led to a lot of sloppy thinking, and is probably the primary reason why evolution is viewed as a soft science by much of society.” (Lynch is also not a fan of the EES. If it were up to him, biology would be even more reductive than the modern synthesists imagined.)

What Lynch has shown, over the past two decades, is that many of the complex ways DNA is organised in our cells probably happened at random. Natural selection has shaped the living world, he argues, but so too has a sort of formless cosmic drifting that can, from time to time, assemble order from chaos. When I spoke to Lynch, he said he would continue to extend his work to as many fields of biology as possible – looking at cells, organs, even whole organisms – to prove that these random processes were universal.

https://www.theguardian.com/science/202 ... -evolution
  • Similar Topics
    Replies
    Views
    Last post

Who is online

Users browsing this forum: Amazon [Bot], Big Daikon, Clutch Cargo, Felgerkarb, Freightdog, IraHayes, Majestic-12 [Bot], Spigzy, xandreu and 574 guests