Latest Sexual dimorphism Stories

It's a question that has puzzled scientists for years: why, in some species of spiders, are the females so much larger than their male counterparts? Now, investigators from the Spanish National Research Council (CSIC) believe they have found the answer.According to their findings, which are published in Wednesday's edition of the open access journal BMC Evolutionary Biology, the cause is likely tied to bridging, a technique of transportation used by some spiders to cross large gaps. When...

Male physical competition, not attraction, was central in winning mates among human ancestors, according to a Penn State anthropologist."There is sexual competition in many species, including humans," said David A. Puts, assistant professor of biological anthropology.Many researchers have considered mate choice the main operator in human sexual selection. They thought that people's mating success was mainly determined by attractiveness; but for men, it appears that physical...

In most animal species, males and females show obvious differences in body size. But how can this be, given that both sexes share the same genes governing their growth? University of Arizona entomologists studied this conundrum in moths and found clues that had been overlooked by previous efforts to explain this mystery of nature.Take a look around in the animal world and you will find that, in most organisms, individuals of one sex are larger than the other of the species.Even though...

Despite their fearsome fangs, male sabertoothed cats may have been less aggressive than many of their feline cousins, says a new study of male-female size differences in extinct big cats.Commonly called the sabertoothed tiger, Smilodon fatalis was a large predatory cat that roamed North and South America about 1.6 million to 10,000 years ago, when there was also a prehistoric cat called the American lion. A study appearing in the November 5 issue of the Journal of Zoology examined size...

Female spiders are voracious predators and consume a wide range of prey, which sometimes includes their mates. A number of hypotheses have been proposed for why females eat males before or after mating. Researchers Shawn Wilder and Ann Rypstra from Miami University in Ohio found, in a study published in the September issue of the American Naturalist, that the answer may be simpler than previously thought. Males are more likely to be eaten if they are much smaller than females, which likely...

Diet can strongly influence how long you live and your reproductive success, but now scientists have discovered that what works for males can be very different for females.In the first study of its kind, the researchers have shown that gender plays a major role in determining which diet is better suited to promoting longer life or better reproductive success.In the evolutionary "battle of the sexes", traits that benefit males are costly when expressed in females and vice versa. This...