Scientists have already concluded why the long neck of the giraffe is advantageous: it gives giraffes a higher vantage point to watch out for danger and to reach vegetation. It also provides a large surface area to regulate body temperature.
But the question of how the giraffe’s physiology allows for such a large distance from its heart to its head has been the focus of a new study. For many years, scientists assumed that giraffes’ long necks were made possible by an abnormally large heart that could pump blood two meters up their necks into their heads.
The recent study by Professor Graham Mitchell from the Centre of Wildlife Studies in Onderstepoort, South Africa proves otherwise. His team has found that the giraffe’s heart is actually smaller than the hearts found in similar-sized animals. However, the walls of the heart are much thicker, which makes for a more powerful pump. In this way, a giraffe’s blood pressure is quite high, but it is physically adapted to handle this heightened state.
For more information about the study, see BBC Earth News.
To learn more about giraffes, read Animal Fact Guide’s article: Giraffe.
Primatologists Emmanuelle Normand, Christophe Boesch, and Simone Ban recently conducted a study focused on the spatial memory of chimpanzees. Using GPS, the team mapped the location of 12,500 individual trees within the home range of a group of chimps in the Tai National Park in Ivory Coast. Then, after tracking which trees the chimps regularly fed from, the researchers found that chimps would specifically seek out certain fruit trees depending on when the fruit was in season.
According to Normand:
“Across all seasons, it seems that they have preferred tree species. Like when it is the coula nuts season, chimpanzees crack nuts using tools for hours during a day. Or when it is the Sacoglottis fruits season, then the chimpanzees stay hours digging their fruit wadge in the water to press a maximum of juice from those fruits.”
The team believes this preference for fruit and the need to remember where the fruit trees are and when they are in season drove the evolutionary development of the primate brain. Another primate who also has a penchant for finding their favorite fruit within a vast forest range is the Bornean orangutan.
For more information about the chimp study, see: BBC Earth News.
Researchers from the journal Science have concluded that elephants in European zoos have shorter lifespans than elephants living in protected areas in Africa. Specifically, they have calculated the median lifespan for a zoo-born African elephant to be 16.9 years as compared with 56.0 years in a protected park. Similarly, Asian elephants born in a zoo live 18.9 years as compared with 41.7 years. Researchers have also found that although survival rates have improved in recent years, mortality rates for elephants in zoos is still significantly higher.
Causes of the shorter lifespans can be attributed to disease, infanticide, obesity, and stress. In the wild or in protected parks, elephants are able to roam vast distances with their herd. At zoos, space is more limited, thereby accounting for some issues like obesity and stress.
The Association of Zoos and Aquariums (AZA) has sharply criticized the study, noting that data was collected from only European zoos as opposed to North American zoos. Further, the AZA contends that the study is flawed because it does not take into account the many elephants who are killed by people in the wild.
For more information:
Boston Globe: Zoo elephants at far greater risk of premature death
New York Times: Critical Report on Health of Zoo Elephants Is Debated
Houston Chronicle: Elephants have shorter lives in zoos, researchers find
For more information about African elephants and what you can do to help them, read Animal Fact Guide’s article: African Elephant.