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 Posted: Thu Jul 10, 2008 7:50 pm Post subject: Why no new species of man? |
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A few hundred thousand years ago, the world population was very smal
yet we had several species of man. In the past 1000 years the world
population has grown orders of magnitude larger, yet how come no new
species have evolved?
My understanding was evolution depends on population and time. The
greater the product of those two, the faster the evolution. So why are
we not seeing radically new species man emerge when more people are
born in one day ( ~4 million ) then lived in the world for milleniums
100,000 years ago. |
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chatnoir
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| Posted: Fri Jul 11, 2008 4:34 pm Post subject: Re: Why no new species of man? |
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On Jul 10, 1:50 pm, oprah.cho...@gmail.com wrote:
[quote]A few hundred thousand years ago, the world population was very smal
yet we had several species of man. In the past 1000 years the world
population has grown orders of magnitude larger, yet how come no new
species have evolved?
My understanding was evolution depends on population and time. The
greater the product of those two, the faster the evolution. So why are
we not seeing radically new species man emerge when more people are
born in one day ( ~4 million ) then lived in the world for milleniums
100,000 years ago.
[/quote]
No reproductive Isolation of a population for one! |
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Tim Tyler
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| Posted: Fri Jul 11, 2008 4:34 pm Post subject: Re: Why no new species of man? |
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On Jul 10, 8:50 pm, oprah.cho...@gmail.com wrote:
[quote]A few hundred thousand years ago, the world population was very smal
yet we had several species of man. In the past 1000 years the world
population has grown orders of magnitude larger, yet how come no new
species have evolved?
My understanding was evolution depends on population and time. The
greater the product of those two, the faster the evolution. So why are
we not seeing radically new species man emerge when more people are
born in one day ( ~4 million ) then lived in the world for milleniums
100,000 years ago.
[/quote]
DNA is old news. These days the cutting edge of evolution is
cultural - and the future lies with the new replicators. In cultural
evolution, developments are indeed happening very quickly.
--
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|im |yler http://timtyler.org/ tim@tt1lock.org Remove lock to
reply. |
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DK
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| Posted: Fri Jul 11, 2008 4:34 pm Post subject: Re: Why no new species of man? |
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In article <g55p6n$cn1$1@darwin.ediacara.org>, oprah.chopra@gmail.com wrote:
[quote]A few hundred thousand years ago, the world population was very smal
yet we had several species of man. In the past 1000 years the world
population has grown orders of magnitude larger, yet how come no new
species have evolved?
My understanding was evolution depends on population and time. The
greater the product of those two, the faster the evolution.
[/quote]
Absolutely. Human evolution *has* been accelerating.
http://www.pnas.org/content/104/52/20753.full
or
http://www.reuters.
com/article/healthNews/idUSN1043228620071210?
feedType=RSS&feedName=healthNews&rpc=22&sp=true
if you don>t have access to PNAS.
[quote]So why are
we not seeing radically new species man emerge when more people are
born in one day ( ~4 million ) then lived in the world for milleniums
100,000 years ago.
[/quote]
Because for new species to emerge, there has to be reproductive
isolation. That>s not what we have. Modern global mobility seems
to work against it. On the other hand, if some tendencies of
positive assortative mating (say, paucity of black-asian marriages
or working class - ruling elite couples) remain or become stronger,
it may be just a matter of time.
DK |
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Lorentz
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| Posted: Fri Jul 11, 2008 4:34 pm Post subject: Re: Why no new species of man? |
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On Jul 10, 3:50 pm, oprah.cho...@gmail.com wrote:
[quote]A few hundred thousand years ago, the world population was very smal
yet we had several species of man. In the past 1000 years the world
population has grown orders of magnitude larger, yet how come no new
species have evolved?
1) Species usually take longer to develop than 25 generations.[/quote]
Assuming that each generation takes 40 years, thats how many
generations occur in 1000 years.
2) New species can>t develop until populations are isolated from each
other.
Human populations aren>t increasing in isolation, they coming
into more contact. In fact, they are interbreeding now more than they
ever did before. If there was ever a chance that American Indians
would evolve into a separate species, the chance disappeared in 1492.
[quote]
My understanding was evolution depends on population and time. The
greater the product of those two, the faster the evolution.
Your understanding is an oversimplification. There are other[/quote]
factors than population and time. In fact:
3) Large interbreeding populations usually evolve slower than small
populations.
Furthermore, to get more species you need diversity in
environment. These days, one human individual can experience most of
the environments available to the human race.
One thing that may help new species evolve would be a mass
extinction. If there were 1000 small tribes of human being left,
separated by large distance, in 1000 different environments, and no
technology to allow them to visit each other, most would go extinct.
However, maybe 10 tribes would to adapt to their environments and
survive up to 1000 generations. Given maybe 1000 generations, maybe
you would have new species. Or maybe even new genuses of humanity.
However, at that point I suspect evolution would stop. Everyone would
adapt to their environments, and equilibria would be established.
If there were periodic mass extinctions, like a similar
identical every 1000 generations, I suspect really big changes would
be made. After 100 such disasters, 1000 generations apart, I suspect
entirely new families and even orders of "humanity" would develop. I
hope this scenario continues to be a fantasy.
To the extent that time makes a difference, I think you should
think of time in terms of generations rather than years. If an animal
reproduces slowly and lives a long time, it won>t evolve very fast no
matter how much time passes. For example, if an animal lives 2000
years and has offspring 500 years apart, obviously there will be no
significant evolution even aft 10000 years. Yet, a flu virus which
reproduces every ten minutes can develop new strains every year. Human
beings with a current turnover rate of about 60 years are not going to
evolve as fast as flu viruses.
Does what I say make sense? |
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