Gene Expression

The title is tongue in cheek, some researchers now are suggesting that speciation may be proportional to a particular energetic value. R.A. Fisher wanted an “ideal gas law” for evolutionary genetics, but this is ridiculous! In any case, one issue that many of us who are interested in paleoanthropology will have noted is that Africa seems to have been the repeated mother of hominid species. That is, “erectus” left around 2 million years ago, only to be swept aside by moderns around 50,000 years ago. Why Africa twice? This might be part of the answer, and is a flip to WIlliam H. Calvin’s Ice Age driven hypothesis in A Brain for all Seasons.

Comments

  1. #1 Rietzsche Boknekht
    May 31, 2006

    In any case, one issue that paleoanthropology will have noted is that Africa seems to have been the repeated mother of hominid species. That is, “erectus” left around 2 million years ago, only to be swept aside by moderns around 50,000 years ago. Why Africa twice?

    It is interesting to note that Africa seems to be the bonebed for hominoid fossil. But how do we know that “erectus” did not become us — i.e., evolved into anatomically modern humans in the myriad niches it inhabited. I know this might sound a little like the Multi-Regional Hypothesis, which, as far as I’m aware, isn’t mainstream anymore, if it ever was. *Why Africa twice* is an interesting question. But based on the “Africa twice” premise, wouldn’t “anatomically modern humans” not have evolved from extra-African “erectus”(unless it re-entered africa early on)? Is extra-African erectus an ancestor of Neanderthals, or of any ancient lineage for which we have fossil evidence? I know that this 50,000 KYA exodus from Africa is supposedly the origin of all modern humans, spreading from east Africa through Asia, from central Asia to Europe & into the Indian-subcontinent; from Asia, to the Americans, Australia, & so on. Personally, alot of this seems a little bit more like story than like solid science. How many *holes*, or rash assumptions are there in this theory that I am not aware of is a question worth asking, IMO. Is some of the theory based on the coalescence of Haplogroups giving a divergence of no more than 50,000KYA — 60,000KYA for all modern global populations, along with some evidence of an exodus of gracile, large-brained hominids from Africa in that timeframe? Should I just take it from the experts, because i don’t have the qualifications to ask questions? My only concern is how much of this rests on shaky ground? Am I unreasonably dubious?

    As far as Global Warming = Future Biodiversity, hmmm.
    An interesting excerpt from the article above, examining the single celled animal, “foramina plankton”:
    It takes more energy than all the fossil fuel people burn on the planet in a year to form one new species of plankton” — and also — “In the end, it is individual metabolic rate – how fast an organism burns food relative to its body weight – that primarily determines evolutionary rate. And higher environmental temperatures help increase metabolism. Diversity is the hallmark of the living

    Interesting findings for their model, but I’m not clear on it. Is this finding implying that it isn’t surprising that equatorial, or hot, humid, niches are the most rich in lifeforms, or simply that life thrives & flourishes in humid heat, or none of the the above? ?:-(puzzled)-:?

  2. #2 SkookumPlanet
    May 31, 2006

    I’d like to read either A Brain for All Seasons or A Brief History of the Mind. The descriptions I’ve seen make them seem very similar and they were published two years apart. Can anyone compare and contrast them for me?

  3. #3 razib
    May 31, 2006

    a brain for all seasons is more thorough. the other one is more just like half a book that seemed published in a hurry.

  4. #4 SkookumPlanet
    June 1, 2006

    Thanks.

  5. #5 Paul S
    June 2, 2006

    It’s always worth remembering that global warming, whether anthropogenic or not, probably doesn’t mean the extinction of life on earth. Life’s pretty adaptable, and will probably go along just fine.

    Of course, that’s not to say that we’ll be there to see it. Global warming very well could wipe out our species along with many others. It could even more easily destroy our cultures and civilizations. So the fact that other critters will adapt and move on is cold comfort to us.

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