The Greater World
Technology For Living Well, Technology in Medicine
We May Be Able To Cope With Climate Change, Through Our Distant
Progeny
Posted by the oracle on Oct 24, 2010 | 8
It will not be through our direct descendants a few studies show,
however. So while those that say we as a race will survive, they may
very well be true, but on the short scale of time, things will get
very rough. It is like asking if you want to make life easier for your
children, or do you want to let nature choose the survival of the
fittest �€" are you willing to roll the dice?
A study of the Yoruba people of West Africa shows that they have
evolved a bit differently than their brethren in Europe and a few
other places. They seem to have a genetic sequence in their DNA which
may help them cope with the arid climate of the Sahara Desert.
[New Scientist]
AS THE climate changes and the world warms, will humans evolve to
handle the effects? Maybe, if the Yoruba people of west Africa's
response to living in arid conditions is anything to go by. Whether
there is enough time to adapt is another matter.
The Yoruba have been exposed, historically, to the dry conditions
of the Sahel on the edge of the Sahara desert. To find out whether
they had evolved to cope, Andres Moreno at Stanford University in
California and colleagues looked at the variation of a gene known to
be involved in water retention in the kidney, called FOXI1, in DNA
samples from 20 Europeans, 20 east Asians and 20 Yoruba.
I�€™m certain there are readers asking if a sampling of 60 people is
enough to accurately determine the possibility �€" no it is not, but
it certainly is enough to help form the hypothesis.
The team found that 85 per cent of the Yoruba had an identical
sequence of genetic information that was longer than it would have
been if it was produced by random recombination and genetic shuffling.
Instead, they suggest that it had been naturally selected (BMC
Evolutionary Biology, DOI: 10.1186/1471-2148-10-267).
The length of the genetic signature suggests that the change
occurred in the last 10,000 to 20,000 years, which could have
coincided with the initial stages of the desertification of the
Sahara. They also analysed a region of the gene in 971 samples from 39
human populations around the world, including the Yoruba, and found
that the same genetic sequence was found at higher frequencies in
lower latitudes. Since lower latitudes are more likely to be regions
of water-stress, this suggests that the selection pressure was climate-
related, says Moreno.
Here we see a study that is statistically significant, and the same
resulting data, which tends to point to correct assumptions. Isn�€™t
the amazing thing about all this how those four building blocks
(adenine, guanine, cytosine, thymine) can combine in so many different
variations, to give such divergent results in all of us?
However, Steve Jones, a geneticist at University College London,
points out that the evidence is only indirect, since we don't know
whether the genetic variance in the Yoruba people actually boosts
their survival.
Nonetheless, if Moreno's explanation is correct, the study opens
up a new question: can humans evolve to adapt to climate change? "Over
the long term, if the Earth keeps warming, I would not be surprised to
see genetic shifts," says anthropological geneticist Anne Stone at
Arizona State University in Tempe.
If the Earth keeps warming it would not be surprising to see
genetic shifts in humans.
Predicting what a human of the future will look like is difficult,
however, as there will be competing selection pressures. Take body
shape. Stephen Stearns, an evolutionary biologist at Yale University,
has suggested that because shorter, heavier women tend to have more
children, who inherit these traits, we can expect the average woman to
be shorter and heavier by 2049. But Stone predicts that because
species in hot environments evolve body shapes that radiate heat
better, climate change will cause humans to grow taller and slimmer.
"It's likely we'll find a sweet spot where we're able to cope with
higher temperatures, but still carry enough fat to be reproductively
successful," she says.
Aside from reproductive success, the major driver of evolution is
differences in mortality. The distribution of disease is expected to
change as the world heats up, for example. The ease of transport and
the global population mean that humans are more at risk of disease
than at any other time in our evolutionary history, Jones says. "If
anything is likely to evolve quickly, it'll be the genes that give you
resistance to disease," he adds.
Evolution is a slow process, however, so any adaptation would not
save us from the imminent problems associated with climate change.
"We're not going to evolve our way out of trouble," says Jones. "The
answer lies in our skulls, not our testicles."
So, as I was saying above, our species may survive, but our direct
descendants may not. Is that what we want?
Humans are still evolving: the evidence
While we may look like the finished article, there is plenty of
evidence that humans are still evolving. John Hawks at the University
of Wisconsin-Madison even argues that population explosions and
rapidly changing lifestyles are causing humans to evolve faster now
than ever before. Evidence includes:
The human brain is still evolving. Bruce Lahn at the
University of Chicago and colleagues identified two genes involved in
regulating brain size that have been subject to recent natural
selection.
The ability to digest milk only evolved in the last 7000
years, says Mark Thomas of University College London.
Genes for early childbirth will be naturally selected for over
time, according to a study by Ian Owen's team at Imperial College
London.
It took just 3000 years for Tibetans to adapt to life at high
altitudes, a record-breaking rate, says Rasmus Nielsen's team at the
University of California, Berkeley.
That last change listed could help us live successfully on a planet
like Mars, after a thin atmosphere was generated, or even the moon,
after we did some terraforming, to ensure a steady supply of small
quantities of oxygen.
The many things we now know about how we adapt will be successfully
harnessed in many areas to make us all better people, but it is a very
slow process, as we change and adapt, and also, learn, a process which
may be slower than others.
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Technorati Tags: climate changes,genetic changes,genetic
predispositions,evolution of man,gene
recombinations,adenine,guanine,cytosine,thymine,evolution progressing
faster than ever before,Saharan adaptations,changes in kidneys,Tibetan
breathing adaptations
Quote of the day:
The greatest of faults, I should say, is to be conscious of none.
- Thomas Carlyle
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