The Ecology Book

123

An alpha male’s body language

says “keep away” to begging chimps

wanting a share of his prey in Gombe

National Park. The main source of prey

for chimps is the colobus monkey.

species. The idea that animal

behavior could be a model for

human behavior took root in the

work of ethologists in the 1950s and

’60s, such as Konrad Lorenz,

Nikolaas Tinbergen, and Karl von

Frisch. Studying animals in their

natural habitats, they saw how

complex the lives of animals were.

They began to understand social

interactions arising from instinct

as well as learned behaviors. The

animal studies held a mirror up

to human behaviors.

The persistent belief that

humans are totally different from

other species was firmly rebutted

with the advent of gene mapping.

When the chimpanzee genome was

mapped in 2005—followed by the

other great apes—and compared

with the human genome, the

results were clear. Humans share

98.8 percent of their DNA with

chimps, 98.4 percent with gorillas,

and 97 percent with orangutans.

Humans and great apes are more

alike than they are different. Yet

it is worth noting that these

percentages are based on genes

that instruct the body how to make

proteins, which make up a very

small part of the human genome

(about 2 percent). It is likely that the

things that make humans different

from chimpanzees can be found in

the regions of DNA called “junk

DNA” because they were previously

thought to be redundant. It is now

understood that this junk DNA

holds vital information about how

and when genes are expressed.

Still, the similarities between the

DNA of humans and the great apes

are striking.

Meat-eating hunters

During her studies, Goodall also

witnessed chimps eating meat

and hunting. As with tool-making,

the idea that chimpanzees were

carnivorous predators went against

all received knowledge. At first,

scientists claimed it was aberrant

behavior, but as the research

continued and more sightings were

made, it became established fact.

Meat-eating has been reported in

just about every area where chimps

have been studied, from Gombe

and Mahale Mountains National

Park, Tanzania, to Tai National

Park, in Côte d’Ivoire. ❯❯

THE VARIETY OF LIFE

Chromosomal

evidence

A strong piece of evidence

in favor of a shared common

ancestor is seen by comparing

chromosomes. Chimpanzees

(and gorillas) have 24 pairs of

chromosomes. Humans have

only 23. Evolutionary scientists

believe that when we diverged

from a common ancestor, two

chromosomes in humans

fused and this is why we have

one less pair than other apes.

On the ends of every

chromosome, there are genetic

markers—or sequences of

DNA—called telomeres. In the

middle of each chromosome

there is a different sequence,

known as a centromere. If

two chromosomes have fused,

it should be possible to see

telomere-like regions in the

middle of the chromosome as

well as at each end. Also, the

fused chromosome would have

two centromeres. Scientists

looked and found just this.

Human chromosome 2 appears

to be the fusion of chimp

chromosomes 2a and 2b. It is

almost beyond doubt that we

share a common ancestor with

chimps, bonobos, and gorillas.

We admit that we

are like apes, but

we seldom realize

that we are apes.

Richard Dawkins

British evolutionary biologist

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