Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Explaining Tsavo’s Maneless Man-Eaters

12.04.2002


The phrase "king of the jungle" invariably conjures up the image of a majestic, tawny cat with a fluffy mane framing its face. But in fact not all male lions have big hair. In Kenya’s Tsavo National Park--famed for the man-eating lions that reportedly terrorized railroad workers there in the late 1800s--a number of males lack manes altogether. Exactly why this should be the case--or why any lions should have manes, for that matter--has been difficult to explain. To that end, the results of a new study, published online today by the Canadian Journal of Zoology, could prove insightful.


Image: John Weinstein/Courtesy of the Field Museum



Over the years, researchers have put forth several social hypotheses aimed at explaining the main function of the mane in these group-living felines, ranging from intimidation (a big mane makes an animal look bigger) to physical protection for the head and neck areas from other lions to sex appeal. At the same time, however, manes are expensive: they offer unnecessary and perhaps harmful insulation to beasts in hot areas, they make the animals more conspicuous to both prey and competitors, and all that extra hair provides more stuff for thorns and brambles to latch onto.

To shed some light on the matter, Roland Kays of the New York State Museum in Albany and Bruce Patterson of the Field Museum in Chicago set out to test one of the social hypotheses: that mane size should vary as a function of female group size. According to this model, increased female group size should ratchet up the sexual selection pressure for long, flowing manes on males. Males with reduced or nonexistant manes, in contrast, should predominate in areas characterized by smaller female groups.


Observations of the Tsavo lions did not bear these predictions out. The researchers found that average female group size was large for the species. Yet most males were maneless or retained only remnant tufts on their head or neck. The more likely explanation for Tsavo’s maneless males, Kays and Patterson conclude, is that the blisteringly hot, arid, thornbrush-covered Tsavo habitat makes mane maintenance too costly.

The researchers further note that in contrast to savannah-dwelling populations, the prides observed in Tsavo consisted of a lone male defending a group of females. "How single, maneless males are able to hold relatively large groups of females remains unknown," they write. But it may be that these males have higher testosterone levels, which could account for both their "baldness" and their ability to single-handedly fend off groups of challengers.

Kate Wong | Scientific American

More articles from Life Sciences:

nachricht Chip-based optical sensor detects cancer biomarker in urine
05.12.2019 | The Optical Society

nachricht Scientist identify new marker for insecticide resistance in malaria mosquitoes
05.12.2019 | Liverpool School of Tropical Medicine

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The coldest reaction

With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction

The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...

Im Focus: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

Im Focus: McMaster researcher warns plastic pollution in Great Lakes growing concern to ecosystem

Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.

In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...

Im Focus: Machine learning microscope adapts lighting to improve diagnosis

Prototype microscope teaches itself the best illumination settings for diagnosing malaria

Engineers at Duke University have developed a microscope that adapts its lighting angles, colors and patterns while teaching itself the optimal...

Im Focus: Small particles, big effects: How graphene nanoparticles improve the resolution of microscopes

Conventional light microscopes cannot distinguish structures when they are separated by a distance smaller than, roughly, the wavelength of light. Superresolution microscopy, developed since the 1980s, lifts this limitation, using fluorescent moieties. Scientists at the Max Planck Institute for Polymer Research have now discovered that graphene nano-molecules can be used to improve this microscopy technique. These graphene nano-molecules offer a number of substantial advantages over the materials previously used, making superresolution microscopy even more versatile.

Microscopy is an important investigation method, in physics, biology, medicine, and many other sciences. However, it has one disadvantage: its resolution is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Detailed insight into stressed cells

05.12.2019 | Life Sciences

State of 'hibernation' keeps haematopoietic stem cells young - Niches in the bone marrow protect from ageing

05.12.2019 | Life Sciences

First field measurements of laughing gas isotopes

05.12.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>