Lecture of the Week: Part I: What Makes Us Human?


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Topic: Science > Physics
User: "Wirt Atmar"
Date: 12 Sep 2006 03:11:02 PM
Object: Lecture of the Week: Part I: What Makes Us Human?
The Evolutionary Biology Lecture of the Week for September 11, 2006 is
now
available at:
http://aics-research.com/lotw/
The talks center primarily around evolutionary biology, in all of its
aspects:
cosmology, astronomy, planetology, geology, astrobiology, ecology,
ethology,
biogeography, phylogenetics and evolutionary biology itself, and are
presented
at a professional level, that of one scientist talking to another. All
of the
talks were recorded live at conferences.
=====================================
September 11, 2006
Part I: What Makes Us Human?
Chimpanzee Comparative Genomics
Andrew Clark
Cornell University
37 min.
"The long hours spent with [the chimpanzees] in the forest have
enriched my life beyond measure. What I have learned from them has
shaped my understanding of human behavior, of our place in nature."
- Jane Goodall
The answer to the question: What makes us human? is greatly confused by
the two dichotomous views we maintain of ourselves. On one hand, we now
know that we share more than 98% of our genes with chimpanzees. On the
other, we see ourselves as fundamentally different beings, possessing
an intelligence and a spirit we don't see in the chimps. If nothing
else, we are a uniquely religious animal. We are wholly aware of our
own impending deaths.
Julian Huxley created the words clade and grade to represent the two
features of evolution that he believed were self-evident. Cladistics
has now become a well established part of the scientific enterprise
associated with understanding the evolution of life on this planet. But
the term "grade" has essentially disappeared from the biologist's
lexicon, if only temporarily, simply because the notion of evolution as
a progressive process has been so deprecated in recent years.
In Huxley's view, clades are defined by common ancestry while grades
are representative of profound evolutionary advances. In his book, New
Bottles for New Wine (1957), he wrote:
"I personally would like to see a new evolutionary classification,
which would combine the advance and ancestry principles. We would have
groups (or 'clades,' from the Greek for branches) of common ancestry
- and grades of advance for which new designations would be needed...
I would hope that Metazoa would be restored to its original use as a
grade label and that Man would be placed in a new major grade, which
might be called Psychozoa."
If it were not for political, social and cultural reasons, humanity,
given any reasonable biology, would be readily assigned to the clade of
the Great Apes. We are clearly that. But we are different too,
currently the sole member of the grade Psychozoa. If there is to be
another species in this grade, the greatest probability will be that
it's one we build ourselves mechanically, a self-aware, conscious being
capable of exploring the galaxy in a manner that we can't. As Seth
Shostak commented in an earlier lecture, "Biological intelligence, as
interesting as it is, may only be a cheap motel on the way to true
galactic intelligence."
During that time when gene sequencing was a new enterprise, requiring
hundreds of people working on a single protein for a year or more, some
of the first investigations into sequencing were done to determine what
form of differences exist between chimpanzee and human. For the first
half-dozen or so proteins sequenced, which were reported over an equal
number of years, no differences were found, leading one wag to say that
"when we're finished with this, the only differences between the
chimpanzee and us will be found to be cultural."
But if we are as different from the other apes as we believe ourselves
to be, then those differences should be reflected in our genetics. The
technology of gene sequencing has seen extraordinary advances recently,
and in this lecture, Andrew Clark presents the results of the most
comprehensive gene-comparison project to date.
The differences found are not what anyone predicted. The most
"accelerated" genes in the evolution of hominids appear in those genes
associated with hearing, signal transduction, amino acid catabolism,
long-bone growth and hairiness, but not in brain function or
architecture, the attributes of our humanity for which we most pride
ourselves.
Post hoc explanations can be created for each of these observed
differences, but post hoc explanations always tread dangerously to
"Just-So" stories. Nevertheless, they're often all we have, and Clark
more reasonably describes them as "hypothesis generators."
Accelerated changes in amino acid catabolisms can be reasonably
explained by the rapid shifts in ecology that the hominid lineage
underwent following its split from the arboreal apes. Similarly,
changes in signal transduction and hearing architectures can likely be
explained not only by the change in sensory environment associated with
an upright gait but also by the necessity of increased oral acuity
accompanying the evolution of language. The difficulties in training
chimps to understand speech may well be attributable to the inadequate
mechanics of their hearing apparatus. Changes in the genetics of
long-bone growth and hairiness seem more obvious yet.
Nonetheless, even if these explanations are true, where is the "gene"
for our self-awareness? To ask that question misunderstands the nature
of complex systems design. The question is akin to asking which piece,
in the thousands of pieces that go into the construction of a jetliner,
determines its flight efficiency? The quality of flight efficiency
doesn't exist in any single rivet or piece of sheet metal, but rather
it pervades all of them. Flight efficiency comes into existence only
after they have been integrated into a working whole. Self-awareness,
intelligence and religiousity are similar qualities and are undoubtedly
so pervasive to our architecture that they may always be below our
technical capacity to find them at any level of statistical
significance.
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