Social evolution in the animal world - conflict
and cooperationIn the early 1970s, Robert L. Trivers presented pioneeringthoughts on the evolution of the social behaviour of animals.These thoughts form the basis today of large parts ofsociobiology, which investigates the origin of cooperation andconflict in the animal world.
Right up to the 1960s, thoughts on the evolution of the social
behaviour of animals were rather undeveloped. Darwin
proposed several hypotheses concerning social evolution in his
time, but these ideas were not picked up by his successors. That
is why this subject has had a dormant existence for a century.
This year´s Crafoord Prize Laureate in biosciences, Robert
Trivers, is one of the small group of pioneering scientists who
began to ponder on the social behaviour patterns of animals
and how they might have arisen through evolution. Between
1971 and 1976, he launched five ideas that have been of the
greatest importance for the development of sociobiology.
They have inspired many behavioural ecologists, who have to a
large extent confirmed Trivers´s ideas.
The first problem he focused on was how evolutionary theory
could explain cooperation between individuals that are not
related. Trivers concluded that cooperation of this kind can
only develop if the animals cooperate over a long period of
time and if they are able to recognise each other. This idea had
an immediate and great impact and Trivers´s thoughts have
later been developed by game theoreticians, among others.
Trivers´s second bid idea deals with the way in which the traits
of male and female animals are influenced by their investment
in their offspring. In a species where the female is responsible
for most of the care, the male will develop traits that the
female likes, for example, colourful plumage, attractive song
or an impressive body size. If the females do not like the male,
he will have poorer chances of passing his genes on to the next
A third hypothesis presented by Trivers is the explanation of
why certain species sometimes give birth to more young of
the same sex. He argued that it could be advantageous, for
example, for a female to give birth to sons when she was in
good condition, since the sons usually grown bigger than the
daughters and therefore demand more energy.
Trivers also explained why conflicts often arise between older
young and their parents. This is not something that only occurs
in teenage families. His interpretation is that when the young
are old enough to take care of themselves, the parents gain by
saving their care for younger or future young. The older young,
on the other hand, want to benefit from their parents´ care as
long as possible.
The fifth idea for which Trivers has been awarded the Crafoord
Prize concerns social hymenoptera: ants, bees and wasps. He
predicted that the workers in an ant community, which are
always female, may be expected to invest three times the
amount of resources in bringing up their sisters than their
brothers. When Trivers later investigated the situation in
reality, the results indicated that he had been right, which later
research also confirmed.
Thus, together with the previous Crafoord Laureates William
D. Hamilton, George C. Williams, Edward O. Wilson and
John Maynard Smith, Robert Trivers has laid the theoretical
foundations for research on the evolution of social behavioural
patterns in animals, a field that is known today as sociobiology
and which is a part of the larger field of behavioural ecology.
Robert L. Trivers, born 1943 (63) in Washington DC, US citizen.
PhD in Biology 1972 at Harvard University, Cambridge, MA, USA.
Professor of Anthropology and Biological Sciences at Rutgers
University, New Brunswick, NJ, USA.
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The Prize-awarding ceremony will take place in Lund on 26 april 2007 in the presence of Her Majesty the Queen.
In 2007 the Crafoord Prize will celebrate its 25th anniversary, with jubilee symposia in Lund 23-26 April. Welcome to four days of plenary lectures, open discussions and symposia in all the Crafoord disciplines. More information at the menu Events.