Are twins exclusive to humans? Certainly they are not found in mice. And what are twins – are they really identical? Answers are emerging – perhaps other primates have twins, and perhaps they are not really identical?
St Clair, J.GB and Golubobovsky, M.D.; Trans from Russian by Lathe, R. and Kotelevtsev, Y. (2008) In the tracks of the Vikings: the search for the twinning gene. Priroda (Nature) 10, 3-15
St Clair, J., Campbell-Palmer, R. and Lathe R. (2014) Sex ratios provide evidence for monozygotic twinning in the ring-tailed lemur, Lemur catta. Twin Res Hum Genet. 17, 1-55