4 ms·

Lice DNA suggests when people first wore clothes

22 points by robg 17y ago

Vivtek 17y ago
"Homo sapiens originated about 200,000 years ago." That figure keeps changing, and it's so fascinating - fascinating enough that I wish they'd given a little more than the bald assertion of the current estimate as though it were long-established fact.
- hugh3 17y ago
  Aren't species boundaries pretty fuzzy when you start trying to look at them across time? A species is defined as a closed set of organisms which can breed with one another. I could breed with someone ten years older, they could breed with someone ten years older than them, and so on into the past until we have an unbroken chain of "could breed with" leading back to reptiles, amphibians, fish and invertebrates with whom I could most definitely not breed (and probably wouldn't want to). But there was no dividing line between "homo sapiens" and "something else" as we go up the chain; there couldn't possibly have been. I get the impression that palaentologists define species by macroscopic features in the fossils, but that they are forced to do so in a fairly handwavey way, so any date when "homo sapiens" really first appeared is pretty arbitrary.
  - CWuestefeld 17y ago
    I think you're mostly right, except that the definition of species comes from does breed with, rather than could. Also, in your example, your ancestor of 10 generations ago cannot breed with one of his contemporaries but 10 years junior, because they're both dead. This isn't hair-splitting, it provides the practical answer to your question. There's no potential for mingling genetic material between those two organisms today.
  - Vivtek 17y ago
    Yeah, but it's really germane to (what I consider) the real question, which is: "When did our path to history start?" I mean, it's a big difference if we had 150,000 years of prehistory, or a million, or 50,000.
    - hugh3 17y ago
      I really don't see what you mean by "our path to history"
nopassrecover 17y ago
The interesting thing for me here was the assertion that mitochondrial DNA was inaccurate for deducing evolutionary timescales. This has important bearings for our current understanding of human evolution which as I understand it is based heavily on mitochondrial data.
- kissickas 17y ago
  >Though well suited to gauging the timing of evolutionary events I think you may have misread that.
  - nopassrecover 17y ago
    I don't think so - they claim it is well suited but simultaneously claim it was wrong by 271% when compared to mitochondrial + nuclear DNA samples because mitochondrial DNA "is a relatively small part of the genome". I thought the advantage of mitochondrial DNA was its stability but if it leads to that margin of error it makes me curious about the reliability of other evolutionary work.
hugh3 17y ago
It’s possible for body lice to have evolved from head lice in only a few generations, according to laboratory studies, Kitchen said. No evidence indicates that head lice can evolve from body lice. This seems like an odd statement. Can anyone provide insight into what this means?

22 points by robg 17y ago

"Homo sapiens originated about 200,000 years ago." That figure keeps changing, and it's so fascinating - fascinating enough that I wish they'd given a little more than the bald assertion of the current estimate as though it were long-established fact.

hugh3 17y ago
Aren't species boundaries pretty fuzzy when you start trying to look at them across time? A species is defined as a closed set of organisms which can breed with one another. I could breed with someone ten years older, they could breed with someone ten years older than them, and so on into the past until we have an unbroken chain of "could breed with" leading back to reptiles, amphibians, fish and invertebrates with whom I could most definitely not breed (and probably wouldn't want to). But there was no dividing line between "homo sapiens" and "something else" as we go up the chain; there couldn't possibly have been. I get the impression that palaentologists define species by macroscopic features in the fossils, but that they are forced to do so in a fairly handwavey way, so any date when "homo sapiens" really first appeared is pretty arbitrary.
- CWuestefeld 17y ago
  I think you're mostly right, except that the definition of species comes from does breed with, rather than could. Also, in your example, your ancestor of 10 generations ago cannot breed with one of his contemporaries but 10 years junior, because they're both dead. This isn't hair-splitting, it provides the practical answer to your question. There's no potential for mingling genetic material between those two organisms today.
- Vivtek 17y ago
  Yeah, but it's really germane to (what I consider) the real question, which is: "When did our path to history start?" I mean, it's a big difference if we had 150,000 years of prehistory, or a million, or 50,000.
  - hugh3 17y ago
    I really don't see what you mean by "our path to history"

nopassrecover 17y ago

The interesting thing for me here was the assertion that mitochondrial DNA was inaccurate for deducing evolutionary timescales. This has important bearings for our current understanding of human evolution which as I understand it is based heavily on mitochondrial data.

kissickas 17y ago
>Though well suited to gauging the timing of evolutionary events I think you may have misread that.
- nopassrecover 17y ago
  I don't think so - they claim it is well suited but simultaneously claim it was wrong by 271% when compared to mitochondrial + nuclear DNA samples because mitochondrial DNA "is a relatively small part of the genome". I thought the advantage of mitochondrial DNA was its stability but if it leads to that margin of error it makes me curious about the reliability of other evolutionary work.

hugh3 17y ago

It’s possible for body lice to have evolved from head lice in only a few generations, according to laboratory studies, Kitchen said. No evidence indicates that head lice can evolve from body lice. This seems like an odd statement. Can anyone provide insight into what this means?