Tag Archives: darwin

Theory by Darwin is proven 150 years after his death

The theory of evolution through natural selection by biologist, geologist, and naturalist Charles Darwin made him one of the most influential people in history. But, in reality, this is not his only contribution to science.

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His investigations supported the concept that humans were animals and members of a single species. He also looked at sexual selection and its influence on beauty, the pollination of orchids, and the evolution of human psychology.

Although he died in 1882, his research still shapes our understanding of the world to this day — and are still relevant scientific topics. A new study by researchers from the University of Cambridge confirmed one of the hypotheses proposed in Darwin’s origins of species.

After analyzing a multitude of studies on small mammals, the researchers have shown that the most diverse lineages have both more species but also subspecies, which confirms that they have a very important role in evolution.

“Darwin said that animal lineages with more species also have to have more varieties, in other words, subspecies,” said in a statement Laura van Holstein, one of the researchers. And that is exactly what has been confirmed, thanks to the analysis of the studies carried out with small mammals.

A species is a group of animals that can reproduce freely amongst themselves. Some species can contain subspecies — populations within a species that differ from each other by having different physical traits and their own breeding ranges. The study confirmed with new experimental data that evolution doesn’t occur in the same way and in the same speed in all mammals since not all of them face the same type of geographical barriers.

“We found the evolutionary relationship between mammalian species and subspecies differs depending on their habitat. Subspecies form, diversify and increase in number in a different way in non-terrestrial and terrestrial habitats, and this, in turn, affects how subspecies may eventually become species,” van Holstein said.

For example, van Holstein said, if a natural barrier like a mountain range gets in the way, it can separate animal groups and lead to different evolutionary journeys. Flying and marine mammals have fewer physical barriers in their environment.

There’s a strong relationship between the diversity of species and the diversity of subspecies, which indicates that the second is very important for the appearance of the first, the researchers argued. In fact, this relationship confirms that subspecies can be considered an early stage of speciation – the formation of new species.

The research represents a warning over the impact humans can have on animal habitats, both today and on their future evolution. The findings can help create new conservation strategies for endangered species across the world.

“Evolutionary models could now use these findings to anticipate how a human activity like logging and deforestation will affect evolution in the future by disrupting the habitat of species,” van Holstein said. “Animal subspecies tend to be ignored, but they play a pivotal role in longer-term future evolution dynamics.”

The study was published in the journal Proceedings of the Royal Society B.

Credit: Pixabay.

Lack of general theoretical framework for human behavior may be to blame for replication crisis in social sciences

Credit: Pixabay.

Credit: Pixabay.

Compared to hard sciences such as physics or chemistry, psychology is notoriously imprecise and prone to bias. By some accounts, about half of the scientific literature in psychology and behavioral sciences cannot be replicated — and the actual figure may be a lot higher if more studies would include participants from non-Western countries. Of course, people aren’t nearly as predictable as the motions of atoms or a chemical reaction, but that doesn’t mean that we don’t have a problem. The solution to this crisis may be a theoretical framework for human behavior which could reorganize the social sciences in the same way that Darwin’s Theory of Evolution reorganized the biological sciences.

This idea was recently proposed by Michael Muthukrishna of the Londons School of Economics and Joseph Henrich of Harvard University. The authors argue that the reproducibility crisis can’t be blamed on flawed methodological and statistical practices (although there are plenty of faults there as well), but rather on the lack of an overarching theoretical framework to create constraints and allow researchers to make predictions from more general premises.

For instance, when physicists at CERN found that neutrinos traveled faster than the speed of light, they immediately suspected that something was wrong because that would violate the theory of special relativity. They then had to devote extra resources and attention to providing more evidence for an extraordinary claim against a tried and tested theory. So, in subsequent experiments, they learned that the initial observation couldn’t be replicated and the theory was strengthened as a consequence. A psychology study, on the other hand, generally lacks the framework that might help researchers to contextualize their findings. For instance, what does it mean that Americans prefer fewer choices to more choices? That’s the finding of a recent study, but is that surprising? Does it violate any theory? Similarly, other studies have argued that people generally conform to majorities. That may be true, but in the absence of a framework, we don’t have the tools to understand when and how people actually do this beyond personal interpretation and folklore.

The authors of the new review suggest that social sciences ought to adopt a framework that might make research more replicable and connect dispersed theories. They propose using a model such as Dual Inheritance Theory, also known as gene-culture coevolution theory. This framework proposes that human behavior is shaped by both biological and sociocultural inheritance systems with their own selective mechanisms and forms of transmission. Biological inheritance is shaped by the information contained in genes, whose evolution follows Darwinian laws of natural selection. Within this framework, researchers previously found that when the environment is stable, it may be more efficient to integrate learning into genetically encoded adaptations. When the environment is unstable, this requires individual trial and error learning, paving the way for cultural transmission.

“After the mathematics of Darwin’s theory of evolution were developed, the next step was a Modern Synthesis with other biologists who had thus far been measuring seemingly disconnected aspects of the biological world. With this new theory of human behaviour, the next step is a new synthesis with other social scientists and the measurements and theories across the social world. For the first time in history, we may be approaching something like a general and unifying theory of human behavior,”  Muthukrishna said in a press release.

These models lead to testable predictions. For instance, Dual Inheritance Theory suggests that social learning is preferable when individual learning is costly, which can explain why copying the majority is beneficial in certain situations. According to previous research, the tendency of humans to copy the behavior of the majority can be mathematically described as an S-shaped curve. For instance, if 60% of researchers used SPSS software for statistical analysis, the probability of a new researcher following the majority is greater than 60%. Similarly, if 60% of your friends prefer McDonalds over KFC, and you haven’t personally tried either yet, there’s a probability greater than 60% that you’ll choose McDonalds as well.

Muthukrishna sees the Dual Inheritance framework like “a periodic table to the social sciences.”

“I don’t think the public is aware of how far we’ve come in understanding why humans are so different to other animals or in understanding how much we understand about the underlying principles behind human behavior. I hope this piece begins to close that gap between the science and public understanding,” he told ZME Science.

The review was published in the journal Nature Human Behavior.

Darwin was proven right by study: life originated on earth, not in the sea

Life on Earth started out in a ‘small little pond’, just like Darwin, the father of evolution, proposed more than 140 years ago, according to a provocative new study.

According to this study, the primordial cells were ‘created’ (though germinated would be a better word) in pools of condensed vapor which appeared as a result of hot water or steam bubbling towards the surface. The finding, which was published in the Proceedings of the National Academy of Sciences challenges the ‘traditional’ view that life originated in the sea, supporting the first true theory of life origin – Darwin’s.

To come to this conclusion, researchers analyzed some key chemical markers in rocks and ancient inland and marine habitats and compared them with a genetic reconstruction of Earth’s first inhabitants. Physics Professor Dr Armen Mulkidjanian, leader of the study, discovered that oceans did not have the right balance of elements to foster life, and instead, found the perfect balance for a ‘hatchery’ inland, especially in places like hot springs and geysers, or where volcanic activity can actively vent hot vapors from beneath the surface.

Researchers noted that these ‘cradles of life’ share all the advantages of the deep sea environment, and also have one crucial advantage: the presence of organic matter. Other scientists seem quite convinced by this study. Prof Mulkidjanian, of Osnabruck University in Germany:

‘I do not think the oceans were a favourable environment for the origin of life – freshwater ponds seem more favourable,’ Nobel laureate Jack Szostak at Harvard University told New Scientist.
‘Freshwater ponds have lower salt concentrations, which would allow for fatty acid based membranes to form.’

Basically similar to Darwin’s idea, this model suggests that life originated on earth and then quickly migrated to the sea. As Darwin put it in a legendary letter to English botanist Joseph Hooker, life may have begun in a ‘a warm little pond’. He then writes:

‘Geochemical reconstruction shows the ionic (chemical) composition conducive to the origin of cells could not have existed in marine settings but is compatible with emissions of vapour-dominated zones of inland geothermal systems. ‘The pre-cellular stages of evolution might have transpired in shallow ponds of condensed and cooled geothermal vapour that were lined with porous silicate minerals mixed with metal sulfides and phosphorous compounds.’

Who said Darwin couldn’t teach us anything new?

First ‘rule’ of evolution suggests life will become more and more complex

crustaceanScientists from the University of Bath have revealed what may very well be the first law of evolution, which has a huge importance. The study was published in Proceedings of the National Academy of Sciences and it shows the fact that evolution drives animals to become increasingly more complex.

They analyzed fossils from the crustacean family tree and drawed conclusions from the different evolutionary branches of the last 550 million years. They were expecting to find animals that evolved to be simpler and more effective, but instead they found that as the evolutionary tree grows, animals tend to be more and more complex than their ancestors.

“If you start with the simplest possible animal body, then there’s only one direction to evolve in – you have to become more complex,” said Dr Matthew Wills from the Department of Biology & Biochemistry at the University of Bath who worked with colleagues Sarah Adamowicz from from the University of Waterloo (Canada) and Andy Purvis from Imperial College London.

But although it may seem strange, 550 mil years may just not be enough time to draw the right conclusions. Dr. Wills adds:

“Sooner or later, however, you reach a level of complexity where it’s possible to go backwards and become simpler again. What’s astonishing is that hardly any crustaceans have taken this backwards route. Instead, almost all branches have evolved in the same direction, becoming more complex in parallel. This is the nearest thing to a pervasive evolutionary rule that’s been found.”

“Of course, there are exceptions within the crustacean family tree, but most of these are parasites, or animals living in remote habitats such as isolated marine caves.