Posts Tagged ‘Chimpanzee’

We walk upright to carry things

March 26, 2012

A new paper reports two studies of Bossou chimpanzees which show that “wild chimpanzees walk bipedally more often and carry more items when transporting valuable, unpredictable resources to less–competitive places”.

Susana Carvalho, Dora Biro, Eugénia Cunha, Kimberley Hockings, William C. McGrew, Brian G. Richmond, Tetsuro Matsuzawa. Chimpanzee carrying behaviour and the origins of human bipedalityCurrent Biology, 2012; 22 (6): R180 DOI: 10.1016/j.cub.2012.01.052

Summary

Why did our earliest hominin ancestors begin to walk bipedally as their main form of terrestrial travel? The lack of sufficient fossils and differing interpretations of existing ones leave unresolved the debate about what constitutes the earliest evidence of habitual bipedality. Compelling evidence shows that this shift coincided with climatic changes that reduced forested areas, probably forcing the earliest hominins to range in more open settings. While environmental shifts may have prompted the origins of bipedality in the hominin clade, it remains unknown exactly which selective pressures led hominins to modify their postural repertoire to include a larger component of bipedality.  Here, we report new experimental results showing that wild chimpanzees walk bipedally more often and carry more items when transporting valuable, unpredictable resources to less–competitive places.

(more…)

Humans prefer to cooperate, chimps don’t

October 18, 2011

Perhaps this was one of the critical genetic traits which – in evolutionary terms – helped humans  separate from the apes and power ahead to be the leading species on the planet.  It is not difficult to imagine that a “cooperation” gene or a “motivation to cooperate” gene – if such a thing exists – could have resulted in a number of “downstream” needs (for communication, language, artefacts, complex social organisations, arts and science) which in turn selected for and influenced the development of the traits which distinguish anatomically modern humans from other primates.

A new paper from the Max Planck Institutes in Leipzig and Nijmegen:

Yvonne Rekers, Daniel B.M. Haun and Michael Tomasello. Children, but Not Chimpanzees, Prefer to CollaborateCurrent Biology, 2011 DOI: 10.1016/j.cub.2011.08.066

 Summary

Human societies are built on collaborative activities. Already from early childhood, human children are skillful and proficient collaborators. They recognize when they need help in solving a problem and actively recruit collaborators.

The societies of other primates are also to some degree cooperative. Chimpanzees, for example, engage in a variety of cooperative activities such as border patrols, group hunting, and intra- and intergroup coalitionary behavior. Recent studies have shown that chimpanzees possess many of the cognitive prerequisites necessary for human-like collaboration. Chimpanzees have been shown to recognize when they need help in solving a problem and to actively recruit good over bad collaborators. However, cognitive abilities might not be all that differs between chimpanzees and humans when it comes to cooperation. Another factor might be the motivation to engage in a cooperative activity. Here, we hypothesized that a key difference between human and chimpanzee collaboration—and so potentially a key mechanism in the evolution of human cooperation—is a simple preference for collaborating (versus acting alone) to obtain food. Our results supported this hypothesis, finding that whereas children strongly prefer to work together with another to obtain food, chimpanzees show no such preference.

Highlights

  • ► First study comparing collaborative motivation between children and chimpanzees
  • ► Children, but not chimpanzees, prefer collaborative over individual food acquisition
  • ► Motivation might be one key factor in the evolution of human-like cooperation

Science Daily

Researchers from the MPI for Evolutionary Anthropology in Leipzig and the MPI for Psycholinguistics in Nijmegen have now discovered that when all else is equal, human children prefer to work together in solving a problem, rather than solve it on their own. Chimpanzees, on the other hand, show no such preference according to a study of 3-year-old German kindergarteners and semi-free ranging chimpanzees, in which the children and chimps could choose between a collaborative and a non-collaboration problem-solving approach. ….

The research team presented 3-year-old German children and chimpanzees living in a Congo Republic sanctuary with a task that they could perform on their own or with a partner. Specifically, they could either pull two ends of a rope themselves in order to get a food reward or they could pull one end while a companion pulled the other. The task was carefully controlled to ensure there were no obvious incentives for the children or chimpanzees to choose one strategy over the other. “In such a highly controlled situation, children showed a preference to cooperate; chimpanzees did not,” Haun points out.

The children cooperated more than 78 percent of the time compared to about 58 percent for the chimpanzees. These statistics show that the children actively chose to work together, while chimps appeared to choose between their two options randomly. ….. Future work should compare cooperative motivation across primate species in an effort to reconstruct the evolutionary history of the trait. …..

Human malaria may have come from gorillas (not chimps)

September 23, 2010

It is heartening to see that science generally works and understanding increases as one discovery leads to another and tentative conclusions from one do not stand in the way of coming to new and different conclusions. Solid and painstaking work in the field and the lab (and not like the so-called science where the grabbing of headlines or the chasing of tenure or generation of funds dominates).

Not very long ago (3rd August 2009) the BBC reported that

Common chimpanzee in the Leipzig Zoo.

Image via Wikipedia

” By looking at blood samples, a US team discovered all world strains of the human malaria parasite falciparum stem from a malaria parasite in chimps. They tell Proceedings of the National Academy of Sciences how the species shift probably happened 10,000 years ago when humans turned to agriculture. Although chimps were known to harbour a parasite – Plasmodium reichenowi – that is closely related to the most common of the human malaria parasites, Plasmodium falciparum, many scientists had assumed that the two had co-existed separately. But blood tests on 94 wild and captive chimpanzees in Cameroon and the Ivory Coast suggest falciparum evolved from reichenowi. Francisco Ayala, of the University of California, Irvine, and colleagues found eight new strains of reichenowi that had striking similarities to falciparum and were genetic precursors to the human disease. The leap could have happened as early as two to three million years ago, but most likely to our Neolithic ancestors as recently as 10,000 years ago”.

But further work reported by the BBC yesterday now shows that the human malaria parasite is more likely to have originated with the gorilla parasite.

Gorilla (Nature)

Gorillas may be the source of human cerebral malaria

“Until now, it was thought that the human malaria parasite split off from a chimpanzee parasite when humans and chimpanzees last had a common ancestor. But researchers from the US, three African countries, and Europe have examined malaria parasites in great ape faeces. They found the DNA from western gorilla parasites was the most similar to human parasites.

Malaria is caused by a parasite called Plasmodium, and is carried by mosquitoes. The most common species found in Africa, Plasmodium falciparum, causes dangerous cerebral malaria. Over 800,000 people die from malaria each year in the continent. Until now, scientists had assumed that when the evolutionary tree of humans split off from that of chimpanzees – around five to seven million years ago – so had Plasmodium falciparum. This would have meant that humans and malaria co-evolved to live together. But new evidence suggests human malaria is much newer. Dr Beatrice Hahn of the University of Birmingham, Alabama, in the US, is part of a team that had been studying HIV and related infections in humans and great apes.

To study the DNA of infections in wild apes, you cannot use blood samples. So the team collected 2,700 samples of faecal material from two species of gorilla – western and eastern – and from common chimpanzees and bonobos, also known as pygmy chimpanzees”.

http://www.bbc.co.uk/news/science-environment-11393664



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