From The Telegraph:
The human genome is littered with sequences left behind from long-ago viral infections but now scientists have found the code is still active
Now researchers at Stanford University School of Medicine have found that genetic material from a retrovirus called HERV-H is not only active, but is crucial in allowing a fertilised human egg to grow into an embryo.
“What’s really interesting is that these sequences are found only in primates, raising the possibility that their function may have contributed to unique characteristics that distinguish humans from other animals.
Let’s back up and be cautious here. For one thing, many primates are not particularly clever, so we need to be much more specific about why it worked (if it did) so well in the human, and not especially in the tarsier. And the way things have been going, the same sequence or a very similar one could turn up in the opossum, but no one has looked. Who knew the water bear shared so many genes with unrelated life forms?
“We’re starting to accumulate evidence that these viral sequences, which originally may have threatened the survival of our species, were co-opted by our genomes for their own benefit.” More.
But we don’t know that either, do we? HERV-H could once have been a useless or even useful parasite that somehow got incorporated into the system.
Question: What were fertilised human eggs doing, to grow into embryos, before HERV-H was available? Or are we to assume it always was available, for all humans? Stay tuned.
See also: Horizontal gene transfer: Sorry, Darwin, it’s not your evolution any more
and This just in: One sixth of water bear’s genes are from microbes Researcher: More than 90 percent of these come from bacteria, but others come from archaea (a distinct group of microbes), fungi, and even plants. “The number of them is pretty staggering,” he says.
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