hu wissen 1 (pdf) - Humboldt-Universität zu Berlin

Peter Hammerstein ist seit 1996 Professor für
»Organismische Evolution« am Institute for
Theoretical Biology (ITB) der Humboldt-Universität.
Er hat Mathematik an der Freien Universität
Berlin und der Universität Bielefeld
studiert. Nach einem Aufbaustudium promovierte
er 1982 unter Betreuung des Evolutionstheoretikers
John Maynard Smith im Fach Biologie.
Seine Doktorarbeit auf dem Gebiet der
Evolutionären Spieltheorie wurde auch von
dem Spieltheoretiker Reinhard Selten betreut,
an dessen Institute of Mathematical Economics
Hammerstein dann als Postdoc arbeitete. Nach
einem längeren Forschungsaufenthalt an der
University of Tennesse in Knoxville habilitierte
sich Hammerstein 1986 für das Fach Theoretische
Biologie, setzte die Forschungstätigkeit
am Max-Planck-Institut für Verhaltensphysiologie
in Seewiesen fort und übte seine Lehrtätigkeit
an der Ludwig-Maximilians-Universität
in München aus. Er war Fellow mehrerer Institutionen
mit dem Titel»Institute for Advanced
Study«, ist externer Professor des Santa Fe Instituts
und gehört zu den Gründern der Zeitschri
»Biological Theory: Integrating Development,
Evolution, and Cognition«. An der
Humboldt-Universität gehört Hammerstein zu
den Gründungsprofessoren des ITB und leitet
seit 2002 den Sonderforschungsbereich »Theoretical
Biology«. Sein Forschungsinteresse als
Evolutionsbiologe gilt den Themen »Konflikt
und Kooperation«, »Economics in Nature« und
»Darwinian Decision Theory«.
Peter Hammerstein has been Professor of
»Organismic Evolution« at Humboldt-Uni versität‘s
Institute for Theoretical Biology (ITB)
since 1996. He studied mathematics at the Free
University Berlin and the University of Bielefeld.
Aer his postgraduate studies he was
awarded a doctorate in biology in 1982 under
the supervision of evolutionary theorist John
Maynard Smith. His doctoral thesis in the field
of evolutionary game theory was also supported
by the game theorist Reinhard Selten, at
whose Institute of Mathematical Economics
Hammerstein then worked as a postdoc. Aer a
long period of research at the University of Tennessee
in Knoxville, Hammerstein qualified as
a professor in theoretical biology in 1986, continued
his research at the Max Planck Institute
for Behavioural Physiology in Seewiesen, and
lectured at the Ludwig-Maximilians University
in Munich. He has been a fellow of several institutions
with the name »Institute for Advanced
Study«, is an external professor at the Santa Fe
Institute and one of the founders of the journal
»Biological Theory: Integrating Development,
Evolution, and Cognition.« At Humboldt-Universität,
Prof. Hammerstein is one of the founding
professors of the ITB and has headed the
Collaborative Research Centre on »Theoretical
Biology« since 2002. His research interests as
an evolutionary biologist include »conflict and
cooperation«, »economics in nature« and
»Darwinian decision«.
estate agent, know all about the value of their territory,« Hammerstein
explains. For example, the evolutionary biologists examine
what happens when an intruder wants to take over a spider’s web.
They noticed that the value of a web is proportionate, among other
things, to the number of insects in it. But how does the intruder
know whether he is fighting for an especially good location for a
web if he has had no opportunity to estimate the number of insects
that have been caught? This question occupied the working
group for a long time, until they found out that the spiders guarding
such a web are stronger than they look and defend their
»property« especially persistently when a stranger comes along. In
other words, they can’t avoid implicitly informing the intruding
spider that it’s worth fighting hard for this web.
Nevertheless, there is only a hard fight in special cases. If
a spider wants to usurp another spider’s web, the opponents start
by making the web vibrate; in this way they can measure their
relative weights without having to touch each other. When spiders
make a decision on whether to respect the opponent’s property,
they usually base this decision on the results of their measurements.
»Evolution has developed a strategy here that helps to
avoid escalation: the enemies assess each other during the fight
and one of them gives up before the battle gets too dangerous,«
explains Hammerstein.
Not only battles, but also collaborations can be explained with
the help of game theory. In repeated games, players can act according
to the »tit for tat« principle. You start with cooperative
behaviour, reflecting the behaviour of the other player which you
had observed previously. In this way, cooperation can be understood
as entirely selfish behaviour. For a long time, biologists
thought that vampire bats acted according to the logic of repeated
games. When a female vampire fails to get a blood meal, she begs
one from another female. And, indeed, it oen happens that a bat
regurgitates the contents of its stomach and gives it to the begging
animal. The conclusion that initially seemed the most logical –
that the animals were acting on a »tit for tat« basis – has not been
confirmed, however. It later transpired that the basis for food being
given away was not some form of internal bookkeeping, but
family relationships between the animals. »We were surprised to
have to admit that a favourite ›baby‹ of the game theorists – titfor-tat
cooperation – doesn’t seem to be a favourite of evolution,«
the biologist sums up.
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