However, the fact remains that yearly there are many
protests and court cases in the U.S. and abroad where people try to block
educational attempts to teach the theory of evolution and replace them with
Fortunately for evolutionary scientists they now have perhaps the greatest
piece of evidence of all -- the largest
evolutionary leap observed to date. The experiment started
inconspicuously, with researchers at Michigan State University in East Lansing
by using a single Escherichia coli bacterium and its descendants to
found 12 populations.
Over 44,000 generations were observed and only minor mutations were observed,
as is typical in these kinds of studies. Typical beneficial mutations --
larger cell size, faster growth rates, and lower peak population densities --
Then at generation 31,500 something shocking happened. The bacteria
evolved, gaining an entirely new gene that could process citrate, a nutrient
that the bacteria could not previously use. To put this in context, lack
of citrate metabolism is one of E. coli's identifying traits. And
the newly evolved bacteria proceeded to dominate over their citrate-intolerant
Says researcher Richard Lenski, "It's the most profound change we have
seen during the experiment. This was clearly something quite different for
them, and it's outside what was normally considered the bounds of E. coli as
a species, which makes it especially interesting."
Lenski says the only two explanations are either an extremely improbable
mutation such as a rare chromosomal inversion, or a series of small mutation
adding up to a useful new gene. Was the trait inevitable, guided by some
all powerful hand? Lenski turned to his freezer for the answer.
Unthawing the bacteria, from early generations, he found that pure chance had
guided the evolutionary leap and that the bacteria did not evolve the
trait. He did find that the later generations after 20,000 did evolve the
trait eventually, indicating something happened around this time that laid the
groundwork for the evolution.
He and his fellow researchers are currently studying exactly what change
allowed for the eventual evolution. This experiment, however, proves that
evolution does not always lead to best possible outcome (in that other lines
did not achieve the same optimal trait). This has been a major point of
contention raised by creationists who point to structures in nature that serve
ornamental or little purpose as proof of creationism.
Further, it goes to show that profound changes can happen, including the
introduction of entirely new genes. A particularly harsh criticism
leveled in the past by was that profound genetic changes, including the
creation of new genes, were never observed. Considering a few genes can
account for profound morphological differences in larger organism, this is a
very salient piece of evidence for evolution's supporters.
Jerry Coyne, an evolutionary biologist at the University of Chicago lauded the
research and took a bit of an opportunity to poke fun at creationists saying,
"The thing I like most is it says you can get these complex traits
evolving by a combination of unlikely events. That's just what creationists
say can't happen."
The findings are reported
in the journal PNAS.