Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period. ||||| If you find yourself looking around the table over the holiday and thinking, “I can’t believe I’m related to these people,” just be glad you’re not a mongoose. If you were, you might be thinking, “I can’t believe I’ve mated with all of these people.” For the cat-sized mammals, native to central and east Africa, it’s safer to have sex with a close relative than risk death by venturing out into the world to find a mate, according to a study published online today in Biology Letters. Newly formed mongoose groups have a mortality rate three times higher than that of established ones, and mongooses that encroach on neighboring groups are often met with violence. Perhaps consequently, an analysis of 14 packs of mongooses in Uganda’s Queen Elizabeth National Park finds that inbreeding is the norm: 63.6% of the pups were conceived between two members of the same natal group, the social group into which an individual is born. Twenty-seven percent of offspring were conceived by mothers that bred within their natal group and were related to their mates by a coefficient of relationship of 0.25 or higher—the equivalent genetic similarity between half siblings or a grandparent/grandchild. Additionally, 7.5% of pups were conceived by parents related by 0.5 or more—full siblings or a parent/child. Father/daughter incest occurred eight times during the study, but interestingly, mother/son breeding was not observed—perhaps due to the fact that males take longer to reach sexual maturity and their mothers are dead by the time they’re ready to mate. Researchers speculate that, at least for mongooses, the genetic problems caused by inbreeding are perceived to be less dangerous than leaving the pack in search of new mates.
– Mammals tend to avoid incest as a rule, mainly due to the resulting health issues in offspring. There are exceptions, however, and a team of researchers has discovered—for the banded mongoose, at least—incest isn't always such a bad idea. The animals have an oddly high degree of incest as they tend to live in close-knit groups of about 18 throughout their lives, according to a study in Biology Letters. Researchers studied 14 such groups of the animals in a Uganda park over 16 years and found about 64% of newborns were born to members of the same natal group who mated with each other. Why? Researchers say a mongoose would actually be risking its survival if it tried to mate with a member of another group, Phys.org reports. Loners who attempt to join a new group can be violently rejected. Plus, new groups have three times the mortality rate of established units. In observing the groups, researchers reported 27% of offspring came from mating between females and relatives like a half-sibling or grandparent, while more than 7% of pups came from parent-child or sibling relationships, Science reports. The conclusion? "The costs of inbreeding avoidance may sometimes outweigh the benefits," researchers say. As David Shultz at Science points out, "if you find yourself looking around the table over the holiday and thinking, 'I can’t believe I'm related to these people,' just be glad you’re not a mongoose." (Seals were recently spotted having sex with penguins.)