How male mam­moths died in ‘silly’ ways

The East African - - MAGAZINE - - New York Times

Swal­lowed by a sink­hole. Washed away by a mud­flow. Drowned after fall­ing through thin ice.

These are the fates that many un­lucky mam­moths suf­fered in Siberia thou­sands of years ago. Their well­p­re­served fos­sils have pro­vided pa­le­o­bi­ol­o­gists with in­sight into their pre­his­toric lives. Now, after per­form­ing a ge­netic anal­y­sis on the re­mains from the furry vic­tims of nat­u­ral traps, a team of sci­en­tists made a strik­ing dis­cov­ery: Most were male.

“In many species, males tend to do some­what stupid things that end up get­ting them killed in silly ways, and it ap­pears that may have been true for mam­moths also,” said Love Dalén, an evo­lu­tion­ary bi­ol­o­gist from the Swedish Mu­seum of Nat­u­ral History.

In a study pub­lished last Thurs­day in the jour­nal Cur­rent Bi­ol­ogy, Dalén and his col­leagues an­a­lysed DNA from nearly 100 mam­moth bones, teeth and tusks, and found that about two-thirds came from males. They spec­u­late the rea­son for the skewed sex-ra­tio may have to do with the risky be­hav­iour that young males ex­hibit after leav­ing the pro­tec­tion of their moth­ers to live on their own.

The find­ing was an ac­ci­dent, said Pa­trí­cia Pečnerová, a doc­toral stu­dent at Stock­holm Univer­sity and lead au­thor on the study. It came while she was en­ter­ing data for a dif­fer­ent project on mam­moth ge­net­ics. “While fill­ing this in on the spread­sheet, we were re­ally sur­prised to see there were more than twice as many males as fe­males be­cause there was no pre­vi­ous re­search or in­di­ca­tion that that should be the case.”

The 98 spec­i­mens that the team an­a­lysed came from the north of Siberia and had been col­lected over the course of four decades. They found that 66 were male and 29 were fe­male. The old­est were more than 60,000 years old, and the youngest, a spec­i­men known as “Lonely Boy,” was about 4,000 years old. The data did not pro­vide in­sight into how old the mam­moths were when they died, only their sex.

The thought is that mam­moths, like today’s ele­phants, lived in ma­tri­ar­chal so­ci­eties where adult fe­males pro­tected the young. But around the ages of 14 or 15 when pu­berty set in, males left their herd and ei­ther be­came lon­ers or joined bach­e­lor groups, which were of­ten led by in­ex­pe­ri­enced males. That was when they were more likely to do some­thing risky, and find them­selves stuck in frozen muck. The nat­u­ral traps buried their bod­ies quickly, pro­tect­ing them from scav­engers.

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