extinction is a world-changing event. In order to qualify, 75
percent of species must be eliminated within a "short" period (between
a few hundred thousand years to a few million years).
This has only happened five times in history, and according to researchers at
the University of California, Berkley, it's happening a sixth time. This time,
they claim humans are to blame.
The worst mass extinction in history occurred during the Permian Period, when
most land species perished. While that won't likely happen, the majority
of non-domesticate large land species may perish over the next a thousand years
if mankind doesn't change its behavior, according to the researchers.
Anthony Barnosky, the curator of the Museum of Paleontology at UC Berkeley and
another co-author of the study, comments that species go extinct today just as
they have always. However, the real question is, "Is the pace of
extinction we're seeing today over these short time intervals usual or
To try to answer that question, Professor Barnosky and his student Elizabeth
Ferrer had to comb both the fossil record and modern conservation biology for
clues. This wasn't easy as the fossil record has plenty of holes and the
best source for modern data -- the International Union for the
Conservation of Nature Red List of threatened and endangered species -- only
has examined 2.7 percent of the planet's 1.9 million named species (which is
likely far from the total species count).
Comparing to historically-known times of normal extinction rate, the pair says
that current extinction rates are conservatively estimated to be 3 to 12 time
higher, with the actual multiplier possibly being as high as 80. Even
under the "best case" 3x scenario, within 22 centuries the world
would reach a "mass extinction" scenario.
The team says we're just on the cusp of causing this. Over the last 200
years we've caused approximately 1 to 2 percent of species to go extinct --
much higher than normal extinction rates. As invertebrate data was still
too week to draw strong comparisons, the study focused its efforts largely on
vertebrate extinction. Its findings were that man is driving the Earth
towards a mass extinction.
The results will likely be the evolutionary
mechanism being kicked into overdrive due to less species, more
resources, and smaller populations of surviving species (allowing for random
In an interview with LiveScience, David Jablonski, a
paleontologist at the University of Chicago who did not participate in the
"If the fossil record tells us one thing, it's that when we kick over into
a mass extinction regime, results are extreme, they're irreversible and they're
unpredictable. Factors that promote success and survival during normal times
seem to melt away."
The study was published [abstract] in
what is arguably the science field's most prestigious journal -- Nature.
The article is drawing a great deal of attention for its comprehensive
review and the startling perspective it provides.
Ms. Ferrer morosely remarks on the attention the study is drawing, "It's
bittersweet, because we're showing that we have this crisis."
Some reacted to the study with prophesies of doom and gloom. Comments
Paul Ehrlich, the president of the Center for Conservation Biology at Stanford
University and author of "The Population Bomb" (Sierra
Club-Ballantine, 1968), "Everything we're doing in Washington [D.C.] today
is working in the wrong direction. There isn't a single powerful person in the
world who is really talking about what the situation is … It's hard to be
cheery when you don't see the slightest sign of any real attention being
Others, like Stuart Pimm, a professor of conservation ecology at Duke
University, were more optimistic. He comments, "If we have a
business-as-usual scenario, it is pretty grim, but it isn't yet written. I hope
that this will alert people to the fact that we are living in geologically
unprecedented times. Only five times in Earth's history has life been as
threatened as it is now."
Regardless of whether the trend continues or reverses, some of the extinction
event's most noticeable changes may be coming soon. Several large land
predator species, including the tiger are
on the verge of extinction in the wild and may vanish within a few
Interestingly, while rainforest destruction continues at a break-neck pace
threatening mass extinction of millions of species, mankind's attention remains
largely wrapped around debating
"climate change" a shift in the Earth's temperatures due to
carbon dioxide -- a change which would contribute far less to the loss of
biodiversity (and could even promote biodiversity in some areas).