Question

Why is that dog produces several puppies at a time whereas human being usually produces only one child at a time?

Answer 1

Fusion of male gametes (sperm) and female gametes(Ovum) leads to the formation of zygotes. A zygote is later developed into a baby.

Dogs are polyovulatory, which means they produce more than one ovum at a time. When these ovum fertilized with sperm, each fertilized egg developed into a baby. So dogs produced many babies at a time.

Humans are uniovulatory which means that only one ovum is produced at a time. As a result, only one baby is produced at a time. In some cases women produce two ova. When these ova are fertilized with sperm they produce two babies.