Evolution And History

Miocene Apes 139

Anthropologist of Note

Allan Wilson

Though a biochemist by training, New

Zealander Allan Wilson has made key

contributions to anthropology through

his pioneering work in applying the

principles of biochemistry to human

evolutionary questions. Wilson forged

a new “hybrid science,” combining

fossil and molecular evidence with

groundbreaking results. Because the

molecular evidence required rethink-

ing long-held theories about the

relationships among fossil groups,

Wilson’s work has been surrounded by

controversy. According to those close

to Wilson, he enjoyed his role as an

outsider—being on the edges of anthro-

pology and shaking things up.

Wilson was born in Ngaruwahia,

New Zealand, and grew up on a farm in

Pukekohe. After attending school in New

Zealand and Australia, he was invited to

study biochemistry at the University of

California, Berkeley, in 1955. His father

was reluctant to have his son travel so

far from home, but his mother saw this

as an opportunity for him and encour-

aged him to head to California.

Wilson stayed at Berkeley for the

next thirty-five years, running one of the

world’s most creative biochemistry labs.

In the 1960s, Berkeley was a center of

academic liberalism and social protest.

Wilson’s highly original work was con-

ducted with a similar revolutionary spirit,

garnering him a MacArthur “genius”

award, two Guggenheim fellowships, and

a place on the short list for the Nobel

Prize.

He developed the notion of a “mo-

lecular clock” with his graduate stu-

dent Vince Sarich and published the

groundbreaking paper “Immunological

Time-Scale for Human Evolution” in the

journal Science in 1967. The molecular

clock proposes that evolutionary events

such as the split between humans and

apes can be dated through an examina-

tion of the number of genetic mutations

that accumulated since two species

diverged from a common ancestor. In

the 1980s, his laboratory (including

Rebecca Cann and Mark Stoneking) was

also responsible for seminal work with

the mitochondrial Eve hypothesis that

continues to be widely debated today

(see Chapters 8 and 9).

Wilson died from leukemia at the age

of 56. Joseph Felsenstein, one of his

biographers, stated in his obituary in the

journal Nature, “while others concen-

trated on what evolution could tell them

about molecules, Wilson always looked

for ways that molecules could say some-

thing about evolution.”

Allan Wilson (right) observes as a laboratory

rabbit is injected.

© Roger Ressmeyer/Corbis

that it was impossible to have a separate human line before
7 mya “no matter what it looked like.” In other words, any-
thing that old would also have to be ancestral to chimps and
gorillas as well as humans. Because Ramapithecus, even with
its humanlike jaws, was dated to between 7 and 12 mya, it
could no longer be considered a human ancestor.
In the meantime, Pilbeam continued fossil hunting in
the Himalayan foothills. Further specimens began to in-
dicate that Ramapithecus was actually a smaller, perhaps
female version of Sivapithecus.^15 Eventually all the speci-
mens referred to as Ramapithecus were “sunk” or absorbed
into the Sivapithecus group, so that today Ramapithecus no
longer exists as a valid name for a Miocene ape. Instead of
two distinct groups, one of which went on to evolve into
humans, they are considered males and females of the
sexually dimorphic genus Sivapithecus. Pilbeam found
a spectacular complete specimen in the Potwar Plateau
of Pakistan, showing that Sivapithecus was undoubtedly
the ancestor of orangutans. This conclusion matched
well with the molecular evidence that the separate line to
orangutans originated 10 to 12 mya.

All of these changes reflect the fact that paleoan-

thropologists participate in an unusual kind of science.

Paleoanthropology, like all paleontology, is a science of dis-

covery. As new fossil discoveries come to light, interpreta-

tions inevitably change, making for better understanding

of our evolutionary history. Today, discoveries can occur

in the laboratory as easily as on the site of an excavation.

Molecular studies since the 1970s provide a new line of

evidence much the same way that fossils provide new data

as they are unearthed. A discovery in the laboratory, like

molecular clocks (now calibrating the split between 5 and

8 mya), can drastically change the interpretation of the

fossil evidence.

The converse is also true. Fossil discoveries can raise

new interpretations of the course of evolutionary his-

tory. The discovery of a 10-million-year-old ape in Ethio-

pia in 2007, thought to be ancestral to gorillas, provides

a case in point.^16 Genetic evidence had pointed to a split

between humans and the other African apes sometime

between 5 and 8 mya. The scientists who found the nine

fossil teeth that resulted in the naming of the species claim

(^15) Pilbeam, D. R. (1987). Rethinking human origins. In R. L. Ciochon &
J. G. Fleagle (Eds.), Primate evolution and human origins (p. 217).
Hawthorne, NY: Aldine.
(^16) Suwa, G., et al. (2007, August 23). A new species of great ape from the
late Miocene epoch in Ethiopia. Nature 448 , 921–924.