Applicance of Science: Only mammals make milk, right? Dr Naomi Lavelle looks at what creatures actually produce milk for their offspring Appliance of Science: Cows do it, we do it, bats and dolphins do it too; we all produce milk to nourish our newborn; it’s what makes us mammals. It turns out that milk-making might not actually be completely unique to us mammals. Mon, 12 Apr, 2021 - 06:00 Cows do it, we do it, bats and dolphins do it too; we all produce milk to nourish our newborn; it’s what makes us mammals. And mammals are the only animals that do this, right? It turns out that milk-making might not actually be completely unique to us mammals.