Sir David Attenborough uses this episode to investigate two animals who are capable of true virgin birth - the production of offspring without the need for sex.
Astonishingly, female Komodo dragons can give birth without ever meeting a male, and breed using just their own set of genes. This process is called parthenogenesis, from the greek for "virgin birth".
Sir David introduces the story of Sungai, a Komodo dragon at the London Zoo, who despite having had no contact with a male for over two years gave birth to four baby dragons. Having first thought that she had stored sperm, it was later found that she had fertilized her own eggs.
For some insects, birth without sex is common place and the advantages are great, with a female aphid being able to create 12 genetically identical daughters a day, and thousands over the course of the spring and summer seasons. Some aphids will even see 40 generations of offspring over the course of the season.
However, we haven't always full understood this. Sir David tells the story of a group of naturalists who solved the conundrum of the aphid reproductive cycle.
But why do Komodo dragons and aphids need this incredible form of reproduction and what are the downsides? We'll let Sir David explain that one in the first episode of David Attenborough's Natural Curiosities.