Sociality and cunningness of hyenas

Carl Zimmer

During the past two decades, Ms. Kay E. Holekamp recorded information about the spotted hyena's life at savanna grasslands south of Kenya. She observes everything from the growing of hyenas and growing up to gain certain positions in the herd until the alliance groups form and break down. She witnessed many skirmishes between herds of hyenas, in which dozens of individuals had to join together to protect their prey areas from invaders.

Dr. Holekamp, ​​who is also a professor at Michigan State University, said: 'This is like dropping a gentle opera song'.

Throughout his career, Dr. Holekamp has always been careful with humanism as the center. She does not think that hyenas are humans with long ears running on four legs. But in fact, the life of the spotted hyena has some similarities with us . Whether in the world of humans or hyenas there exists a complex society that drives the evolution of the brain.

Hyenas at Masai Mara National Reserve and at Amboseli National Park (Kenya) - (Photo: Nytimes)

Scientists have long wondered about the enormous size of the human brain. It is 7 times bigger than the brain of an individual mammal the size of us. Many additional neurons are concentrated in the frontal lobe where numerous complex neurological activities take place.

To find out why we have such a strange organism, scientists have turned to primates - our relatives. They also have large brains although not as large as humans. Primates with developed frontal lobes tend to live in groups.

Primates can live in large groups due to the effects of predators or because of the binding role of food sources (such as fruit trees). As the number of individuals in the herd increases, natural selection will prioritize intelligence. Individuals that join together form a long-term alliance and compete with rivals. And they also started tracking an increasingly large social network.

The promotion of social intelligence can lead to a revolution for primates . For example, female baboons with good bonding will dominate the whole herd. They will have more children than their subordinates, and their offspring are also healthier and grow better.

Brain imaging studies have revealed that when people think about others, some parts of the frontal lobe work. Proponents of social mind theory argue that our ancestors' frontal lobes are complex because natural selection prioritizes social intelligence.

Most studies of the social-minded hypothesis focus on primates. According to Dr. Holekamp, ​​one reason for this trend is that many scientists think that no other animal is worthy of research.'Primate researchers have been arguing for years that primates are unique creatures in terms of complexity in their social life.'

From the experience gained from hyenas, Dr. Holekamp has a basis to doubt the above arguments. Therefore, she embarked on experiments for spotted hyenas similar to those on primates. She will turn on the recording of hyenas to see if other children recognize it or not. The answer is yes. She quickly found that the point of view of the only existential social mind in primates was incomplete.

Dr. Holekamp said: 'I will prove that it is not true: spotted hyenas live in crowded and complex herds like baboons .' She also stressed that spotted hyena individuals exist in the most crowded social environment of any predator. 'We are talking about a herd of hyenas with about 60 to 80 individuals while they all know each other clearly.'

By scanning the hyena's brain image, scientists can find out the structure of the brain.Primates with developed frontal lobes tend to live in the herd.(Photo: Nytimes)

To understand the social intelligence of hyenas, Dr. Holekamp and his colleagues followed animals from birth to death. The study proceeds in caves where young children live the first few days of their parents. Must crawl to the inside of the cave as well as a network of underground areas that is the least interesting of Dr. Holekamp.

She said: 'Studying hyenas has little trouble because we know when there is a mother in the cave and when it is outside. However, what's inside of a boar that is willing to give you a fang or a cobra cobra? '

More mature spotted hyenas often visit the cave to teach young children about the strict hierarchy in their society. All spotted hyenas have a female head and a series of subordinates. Each calf must learn exactly its proper position in the herd scale and all other spotted hyenas must adapt.

The hierarchy itself proved very lively when mealtimes arrived. If one or two children are in the herd, other members of the group will attend to fight the prey. But the first children always win.

Dr. Holekamp said: 'The leading children can attend any hunt and eat as much as they want'.

However, there were times when the whole herd of hyenas gathered. The spotted hyenas often travel along the territory and then mark with urine. If there is a hunt that happens near the border, a conflict with the neighboring hyenas may erupt. Dr. Holekamp said: 'When a territorial dispute occurs, all unrelated individuals also participate in the group or the other in the territorial battle'.

Kay E. Holekamp of Michigan State University recently learned about the life of a spotted hyena in Kenya to find out the relationship between any set size and sociality.(Photo: Nytimes)

According to Dr. Holekamp, ​​what sheds light on the social complexity of the spotted hyena is their relative. Spotted hyenas are located in a large family divided into 4 species, three other species live in a very different society.

For example, brown hyenas live in smaller colonies with about 14 individuals. Although scientists still do not have much information about brown hyenas, it seems that some brown hyenas live in a hierarchy, while in others, individuals are more equal.

The striped hyenas live in smaller groups, including only one female and no more than three adult males. Males mate with females, but they seem to have no other work to do with her.

The most solitary species of the spotted hyenas is the earth wolf. Instead of hunting or eating corpses, they switched to diet mode from the termites. Male and female wolves live in individual pairs, taking care of their young and protecting their termites from intruders.

Dr. Holekamp wondered if this social order system was reflected in the hyena's brain structure. This is not easy to verify. She said: 'The brain is not like hyenas on savanna grassland. It's really hard to control them. '

While understanding the intact brains of hyenas is extremely difficult, manipulating this animal's skull is not that difficult. By using the hyena of the hyena, the three-dimensional structure of the inner brain can be reconstructed.'You will see all the grooves or curves on the surface of the brain,' said Dr. Holekamp.

In recent months, Dr. Holekamp has collaborated with Sharleen Sakai and Barbara Lundrigan (in the state of Michigan) in the process of surveying dozens of skull patterns of all four species in the hyena family. Preliminary results show that hyenas also follow the same rules as primates.

According to Dr. Holekamp, 'this is exactly what the hypothesis of social complexity should present. Hyenas that live in the simplest social system have the least developed frontal lobe. The spotted hyena lives in the most complex society, the largest developed frontal lobe . Brown hyenas and striped hyenas have a moderately developed social system that also has a moderate frontal lobe. '

Joan Silk - a monkey life expert at the University of California (Los Angeles) - praised Dr. Holekamp's research and said that it ' is directly related to our understanding of the origin of complexity in society as well as social intelligence '.

Although hyena's intelligence can be similar to that of primates, Dr. Holekamp must also be confused with differences. Primates are very curious, while she does not notice many signs of creativity in hyenas. She said: 'It may not be a fair question. Perhaps we will have to ask this question in relation to other carnivores - in that environment we want the hyena to be extremely curious and creative. '

To get the answer to the question, Dr. Holekamp and his colleagues have been conducting experiments on intelligence in wild hyenas. Scientists put meat in the boxes and left it on savanna grassland. Dr. Holekamp said: 'The hyena can see and smell, but it cannot take a piece of meat unless it finds a way to pull the key from the right to the left as the door opens'.

Dr. Holekamp hopes to know how hyenas are creative compared to other carnivores. Maybe besides social complexity, intelligence has evolved in some way.'Animals will be given priority to develop creativity if that property helps it get food regardless of whether it lives in the pack or alone'.

By comparing between hyenas and primates as well as other mammals, Dr. Holekamp believes that she will get a complete picture of the evolution of intelligence. She said: 'Although the social-minded hypothesis has a huge support base, I still believe that in order to understand the origin of intelligence, we must think more deeply than that hypothesis.' .

Social life of spotted hyena (Photo: Nytimes)