Close up on research

The Ant Man

By Hubertus Breuer

He has received a Pulitzer Prize for his work, moves back and forth between universities in Germany and the USA, and is one of the world’s leading experts in myrmecology. For over fifty years, Bert Hölldobler has been researching the world of ants.

Photo: Bert Hölldobler

The year was 1944. Bert Hölldobler was all of seven or eight years old. His father, a surgeon who had studied zoology, was home on leave from the Eastern Front. They were rambling through the Franconian Forest near Ochsenfurt together, his father turning over stones to look for ant crickets. Under one of those stones, the boy suddenly caught sight of a colony of carpenter ants scurrying about, rushing their larvae and pupae to safety, vanishing into the tunnels that protected them from the light of day and the prying eyes of father and son.

A carpenter ant worker helps a young worker to hatch from the cocoon.
A carpenter ant worker (Campo-
notus ligniperdus
) helps a young
worker to hatch from the cocoon.
It was an encounter with this
species of carpenter ant on a
ramble with his father at the
age of seven or eight that became
a formative experience in the life
of Bert Hölldobler.

Photo: Bert Hölldobler

Hölldobler, 77, recounts this formative experience in his office at Arizona State University. Sitting at his desk, a wiry man in short sleeves with a beard and lively blue eyes, he has the air of an outdoorsman just returned from an excursion into the Bavarian Forest or the desert.

Today, the scientist, whose involvement with the Alexander von Humboldt Foundation goes back to 1973, is one of the world’s leading experts on research into ant societies. He illuminated their complex social life, publishing the Pulitzer Prize-winning, definitive work “The Ants” together with Edward O. Wilson, the pop star of American evolutionary biology, while he was at Harvard University in 1990. In recent years, Hölldobler has joined forces with bee geneticist Robert Page to set up an international group of researchers at Arizona State University’s School of Life Sciences to examine the complex social behaviour of bees, ants and termites.

The rove beetle is completely integrated in the ant society.
The rove beetle Lomechusa
is completely integrated
in the ant society, in this case
Formica sanguinea. In this
Picture a Lomechusa beetle is
being fed by a worker ant at one
end while pacifying another worker
with the secretion from a gland
at the tip of its rear end.

Photo: Bert Hölldobler

Beetles that behave like ants

Academically, ants first crossed Hölldobler’s path in his student days, when he discovered that carpenter ants in Europe’s far north operate an unusual system of reproductive ant stockpiling: the male and the female alates are produced one year before their mating flight. And because it would be rather uneconomical if the males did nothing but consume food for months, they exhibit an extraordinarily high level of social behaviour and help in caring for the brood, for example. This is quite different from the vast majority of ant species, in which the males swarm out as “sperm rockets”, as Hölldobler terms it, in the year they are born, mate, if they are lucky, with a future queen, and then die.

Hölldobler made sensational discoveries from the early days of his career. It had long been known that other insects, such as rove beetles, live in ant colonies as social parasites: the ants raise the beetles’ larvae, and feed and protect the adult beetles. Hölldobler wanted to find out how that was possible, as ants are renowned for hunting and devouring intruders. He was able to prove that over the course of evolution, the parasitic beetles had deciphered the ants’ communication code and could mimic it so effectively that the ants fed and cared better for them than for their own larvae and nestmates. The results of this work made it into prestigious academic journals like “Science” – the first highlight of Hölldobler’s young career. Many other papers on chemical communication in ants followed.

Bert Hölldobler in the field in Arizona, filming a territorial battle between honeypot ants.
Bert Hölldobler in the field in
Arizona, filming a territorial
battle between honeypot ants.

Photo: Turid Hölldobler-Forsyth

These achievements bore fruit – in the autumn of 1969, Hölldobler accepted an invitation to spend a year conducting research at Harvard University. His work there was so successful that one year became two. The US university was a revelation. After Frankfurt’s endless meetings blighted by irrelevant points of order that brought university business almost to a standstill, he found himself in Cambridge, USA, where he was not only able to conduct his research without the bureaucracy, but also encountered a highly stimulating environment. He formed close academic ties with Edward O. Wilson, and with insect physiologist Carroll M. Williams and his group. He also attended lectures by the then grand old man of evolutionary biology, Ernst Mayr, who became a paternal friend over the years. During his research stay at Harvard, Hölldobler was notified that he had been appointed professor of zoology in Frankfurt, which came as something of a surprise as he had not actually applied for the post. And so he returned to Frankfurt – a decision he was soon to regret.

Fleeing the Frankfurt 68ers

Once there, he came face to face with the aftermath of the 1968 student revolution. Liberal though Hölldobler may be, he found himself forced to witness his teacher Lindauer being bombarded with paper planes and pellets during lectures. He soon thought of leaving Frankfurt again. When first Cornell University, and shortly afterwards Harvard, offered him full professorships in 1972, he said yes to Harvard.

View of a chamber in an ants’ nest with rows of honeypots hanging from the roof
View of a chamber in an ants’ nest
with rows of Myrmecocystus
honeypots hanging from
the roof.

Photo: Bert Hölldobler

Hölldobler’s association with the Alexander von Humboldt Foundation also goes back to his time at Harvard when he became an expert reviewer for the Foundation’s new Humboldt Research Award Programme. Later, in 1987, he received the Humboldt Research Award himself. When he finally moved to Würzburg in the autumn of 1989, to head the newly conceived Department of Behavioural Physiology and Sociobiology, he became a member of the selection committee for the award, a function he performed for ten years. “That was a nice job, because many excellent academics from abroad were invited to Germany for a research stay through this programme.”

His move to Würzburg was not only prompted by homesickness. Despite a steady flow of grants from the National Science Foundation Hölldobler had been unable to set up a large-scale interdisciplinary working group with geneticists and neurobiologists in the USA. The newly founded Biocenter in Würzburg on the other hand brought together biological disciplines from three faculties. That appealed to Hölldobler. And that on top of all he won the Leibniz Prize in 1990, “that was a real bonanza”, he notes. He was able to invite many researchers to Würzburg from Germany and abroad, an endeavour for which the Humboldt Foundation also provided considerable assistance.

Ritual displays instead of bloodshed

Territorial battles between African weaver ants. Both the enemies and the fellow ants that have been killed in battle are carried back to the nest and used as food.
Territorial battles between African
weaver ants. Both the enemies and
the fellow ants that have been
killed in battle are carried back to
the nest and used as food.

Photo: Bert Hölldobler

Even today, in Arizona, Hölldobler’s work is far from over – he is extending his research into the evolution of social insects, working with colleagues from a wide range of disciplines. Among other things, the myrmecologist is examining the aggressive behaviour of ants like the honeypot ant. Workers from neighbouring colonies confront each other in ritual displays in which they posture with raised heads and rears. Similar behaviour can be observed in other species. Groups of woodhoopoes, an African bird species, for example, conduct calling contests with other flocks – the winner is whoever calls the longest and loudest. And native people in New Guinea are also known for such ritual combat during which not a single drop of blood is shed; its purpose is to demonstrate a tribe’s battle strength to its opponents.

So his work continues, but Hölldobler is also satisfied when he looks back. He is considered one of the world’s pre-eminent researchers in his field. Many of his former collaborators have themselves made important contributions to science and are now professors with international reputations. And, last but not least, he has managed over the years to achieve one of his prime objectives and communicate his research to a wide audience, as evidenced by another of his books, “Journey to the Ants”, which has just appeared in Germany entitled “Auf den Spuren der Ameisen”.

published in Humboldt Kosmos 100/2013