Posts tagged natural selection
Articles and news from the latest research reports.
Networking Ability a Family Trait in Monkeys
Two years of painstaking observation on the social interactions of a troop of free-ranging monkeys and an analysis of their family trees has found signs of natural selection affecting the behavior of the descendants.
Rhesus macaques who had large, strong networks tended to be descendants of similarly social macaques, according to a Duke University team of researchers. And their ability to recognize relationships and play nice with others also won them more reproductive success.
"If you are a more social monkey, then you’re going to have greater reproductive success, meaning your babies are more likely to survive their first year," said post-doctoral research fellow Lauren Brent, who led the study. "Natural selection appears to be favoring pro-social behavior."
The analysis, which appears in Nature Scientific Reports, combined sophisticated social network maps with 75 years of pedigree data and some genetic analysis.
Human hands have ‘evolved for fighting’
Compared with apes, humans have shorter palms and fingers and longer, stronger flexible thumbs. Experts have long assumed these features evolved to help our ancestors make and use tools. But new evidence from the US suggests it was not just dexterity that shaped the human hand, but violence also.
Hands largely evolved through natural selection to form a punching fist, it is claimed. ”The role aggression has played in our evolution has not been adequately appreciated,” said Professor David Carrier, from the University of Utah.
”There are people who do not like this idea but it is clear that compared with other mammals, great apes are a relatively aggressive group with lots of fighting and violence, and that includes us. We’re the poster children for violence.”
The forces of natural selection that drove hands to become nimble-fingered also turned them into weapons, Prof Carrier believes.
”Individuals who could strike with a clenched fish could hit harder without injuring themselves, so they were better able to fight for mates and thus be more likely to reproduce,” he said.
”If a fist posture does provide a performance advantage for punching, the proportions of our hands also may have evolved in response to selection for fighting ability, in addition to selection for dexterity.”
Human Evolution Enters an Exciting New Phase
“Most of the mutations that we found arose in the last 200 generations or so. There hasn’t been much time for random change or deterministic change through natural selection,” said geneticist Joshua Akey of the University of Washington, co-author of the Nov. 28 Nature study. “We have a repository of all this new variation for humanity to use as a substrate. In a way, we’re more evolvable now than at any time in our history.”
Yeast experiment offers fresh insights on the nature of natural selection
An experiment involving yeast has revealed a method that allows organizations to avoid the “tragedy of the commons,” the situation in which individuals take advantage of shared resources — such as common grazing land for animals — without paying for their use or maintenance.
By performing the experiment on small organisms, researchers have shown a way to avert a prediction of evolution theory: that natural selection necessarily favors “cheaters” — individual organisms determined to game the system — over “cooperators” who obey the rules.
The experiment, reported in Proceedings of the National Academy of Sciences, reveals a way in which evolutionary adaptation via mutations can benefit cooperators over cheaters.
"It gives a larger role to adaptation," said Adam Waite, a graduate student in molecular and cellular biology at the University of Washington, who performed the research with his supervisor, Wenying Shou, at the Fred Hutchinson Cancer Research Center in Seattle. "While natural selection should help cheaters, it can also help cooperators defeat cheaters."
Evolution of new genes captured
Like job-seekers searching for a new position, living things sometimes have to pick up a new skill if they are going to succeed. Researchers from the University of California, Davis, and Uppsala University, Sweden, have shown for the first time how living organisms do this.
The observation, published Oct. 19 in the journal Science, closes an important gap in the theory of natural selection.
Scientists have long wondered how living things evolve new functions from a limited set of genes. One popular explanation is that genes duplicate by accident; the duplicate undergoes mutations and picks up a new function; and, if that new function is useful, the gene spreads.
"It’s an old idea and it’s clear that this happens," said John Roth, a distinguished professor of microbiology at UC Davis and co-author of the paper.
The problem, Roth said, is that it has been hard to imagine how it occurs. Natural selection is relentlessly efficient in removing mutated genes: Genes that are not positively selected are quickly lost.
How then does a newly duplicated gene stick around long enough to pick up a useful new function that would be a target for positive selection?
Experiments in Roth’s laboratory and elsewhere led to a model for the origin of a novel gene by a process of “innovation, amplification and divergence.” This model has now been tested by Joakim Nasvall, Lei Sun and Dan Andersson at Uppsala.