MadSci Network: Genetics

Re: Is there yet any evidence which suggests extraterrestrial intervention?

Date: Mon Apr 1 14:25:19 2002
Posted By: Christopher Carlson, Senior Fellow, Dept. of Molecular Biotechnology
Area of science: Genetics
ID: 1017464850.Ge

Hi Clay,

You ask a rather interesting question, and one which I must admit we
haven't much data to address.  However, part of the fun of science is
speculating on the possibilities in light of current knowledge.  So here

I'm interpreting your basic thesis as "Humans aren't particularly well
adapted to our current ecological niche, whereas other animals seem well
adapted to their niches.  Therefore it is possible that these
maladaptations came from aliens."  I'm not sure if you're familiar with
Occam's Razor.  It's a simple little rule that states that the simplest
answer is usually correct.  So let's see if there might be a simple answer
for why humans are so badly adapted which relies on biological rules where
we have strong evidence, as opposed to aliens, where the evidence is pretty

First I want to examine the premise that humans are poorly adapted to the
environment.  Although a naked human being doesn't really stand much of a
chance anywhere in the world, we have occupied virtually every environment
available, from the islands of Polynesia to the mountains of the Himalayas,
from the deserts of the Middle East to the jungles of Central America.  How
could a poorly adapted animal succeed in so many environments?  The answer
is that human adaptation long ago made the leap from genetics to culture. 
For example, it's a lot easier (and faster) to learn to wear pelts than to
grow hair all over.  Same goes for learning to make spears vs. growing
fangs.  I'm just trying to point out that it doesn't make sense to look at
how well humans are adapted to the environment without looking at our
tools, and from this standpoint we are tremendously well adapted to the world.

Of course, this does come with a caveat.  Lower back pain (and difficult
child birth, for that matter) do indeed represent maladaptations to walking
upright.  There's a lot of debate at the moment about why we started
walking upright in the first place, whether it was a cause or a consequence
of tool use or envirnmental change.  The important part is that it was a
relatively recent adaptation compared to most other traits (grasping hands,
color eyesight, etc.) and therefore the kinks haven't entirely been worked
out yet.  Given the size of the current human population and the pace of
technological adaptation, it's pretty likely that genetic evolution as we
knew it is over for the human species.  We're much less likely to evolve to
survive the modern diet than we are to find ways to produce a healthy Twinkie.

Returning to your original question, the DNA of every human is 99.9%
identical to every other human, regardless of race.  Perhaps more
surprising is that human DNA is 98 to 99% identical to chimps.  Based on
the fossil record this is a reasonable divergence, and can be explained as
a simple consequence of time and the mutation rate of DNA.  So using
Occam's Razor, because we can explain human adaptation using simple systems
we know a lot about (mutation, evolution, and cultural adaptation), alien
DNA is pretty unlikely.  I know this may be a bit disappointing to X-Files
fans, but I long ago gave up hope that their writers would try to keep the
science in their science fiction in the realm of the possible, much less
the plausible.


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