The Top 10 Mammals With the Longest Gestation Periods

With the average human pregnancy lasting 40 weeks (280 days) you might start to understand why our population is growing so fast when you take a look at these ten. They are the top 10 mammals with the longest gestation periods and they make us humans look like baby producing machines… The Top 10 Mammals With the Longest Gestation Periods   10 – Llama – Average Gestation Period: 360 Days The gestation period of a llama is 11.5 months (350 days). Dams (female llamas) do not lick off their babies as they have an attached tongue that does not reach outside of the mouth more than half an inch (1.3 cm). Rather, they will nuzzle and hum to their newborns.