“Researchers have been able to trace a line between some of the earliest modern humans to settle in China and people living in the region today.
The evidence comes from DNA extracted from a 40,000-year-old leg bone found in a cave near Beijing.
Posts tagged evolution.
Projecting human evolution: 5 traits we might possess in the futureA recent study out of the University of Sheffield has found that humans are still subject to Darwinian selection, in spite of the modern wonders of medicine and technology.Of course, the idea that humans are still evolving is one that has never been legitimately questioned. In fact, according to an evolutionary principle called the Hardy-Weinberg equilibrium, evolutionary change is a mathematical necessity so long as at least one of the following influences occur to a genetic population: mutation, non-random mating (including sexual selection), gene flow, genetic drift or natural selection.
(Phys.org) Males and females… Mars and Venus… XY and XX chromosomes, all are common memes. At the same time, the evolution of therian (placental and marsupial) sex chromosomes is less widely understood. More to the point, these arose some 150 million years ago from a pair of autosomes, or non-sex chromosomes. Having appeared, the X and Y chromosomes – both with the same ancestral genes – began diverging, with the Y chromosome evolving into a state in which (except for two small autosomal regions) it never recombines. As a result, the Y chromosome has degenerated, losing most of its genes in the process. On the other hand, the X chromosome does recombine, retains many ancestral genes – and has gained new genes, and evolved new expression patterns, as well. The increased imbalance of X/Y chromosomal loci led to the emergence of loci-specific X chromosome inactivation, which has been seen as compensating for differential gene dosage (the number of copies of a given gene present in a cell or nucleus) by making expression of X-linked genes similar in males and females.
The rogue proteins behind variant CJD, the human form of mad cow disease, have revealed their benign side. Prions, it seems, lie at the heart of a newly discovered form of near-instant evolution that provides life with a third way to adapt to potentially lethal environments. Crucially, it involves neither genetic nor epigenetic changes to DNA.
The conventional view is that new traits can only evolve if DNA itself changes in some way. The classic way to do this is by mutating the genetic code itself. More recently, researchers have discovered that molecules can clamp onto DNA and prevent some parts of the sequence from being read, leading to genetic changes through a process that is known as epigenetics.
“What people haven’t seemed to notice is that on earth, of all the billions of species that have evolved, only one has developed intelligence to the level of producing technology. Which means that kind of intelligence is really not very useful. It’s not actually, in the general case, of much evolutionary value. We tend to think, because we love to think of ourselves, human beings, as the top of the evolutionary ladder, that the intelligence we have, that makes us human beings, is the thing that all of evolution is striving toward. But what we know is that that’s not true.
Obviously it doesn’t matter that much if you’re a beetle, that you be really smart. If it were, evolution would have produced much more intelligent beetles. We have no empirical data to suggest that there’s a high probability that evolution on another planet would lead to technological intelligence.”
Tim Maudlin, (B.A. Yale, Physics and Philosophy; Ph.D. Pittsburgh, History and Philosophy of Science), ☞ What Happened Before the Big Bang? The New Philosophy of Cosmology, The Atlantic, Jan 2012.
Neanderthals Had Differently Organised Brains
Homo neanderthalensis is not a species to be dismissed lightly. They weren’t especially dumb, nor especially weak. Indeed, they actually had larger brains and denser muscles than we did.
On top of that, their technology was so well adapted to their environment that they were able to flourish without drastically altering it for hundreds of thousands of years. It was just that good.
So it would seem we have no clear advantage over them, which makes the fact we survived but they did not especially puzzling.
Recent research argues this might have been because their brain, despite being bigger, ultimately had a more primitive shape. Our frontal and temporal lobes are a different to theirs and our olfactory bulb is larger. Could our brain shape have given us an advantage?
Now, new information presented at the HOBET conference I recently attended lends further credibility to that hypothesis.
Under artificial pressure to become larger, single-celled yeast became multicellular creatures. That crucial step is responsible for life’s progression beyond algae and bacteria, and while the latest work doesn’t duplicate prehistoric transitions, it could help reveal the principles guiding them.
“This is actually simple. It doesn’t need mystical complexity or a lot of the things that people have hypothesized — special genes, a huge genome, very unnatural conditions,” said evolutionary biologist Michael Travisano of the University of Minnesota, co-author of a study Jan. 17 in the Proceedings of the National Academy of Sciences.