Darwin's Second Postulate

By: Juan Flores


Darwin has four postulates, as explained in the first bulletin; In this post, we're going to talk about Charles Darwin's second postulate, Inheritance, which is a simple topic. When two participants of a species mate, they combine chromosomes containing their DNA and information to create a new being. For example, a male human has the XY chromosomes while women have XX chromosomes. If the combination ends with a Y, it means that the being will be male, and if it has XX's it means it is a female. This doesn't relate with inheritance though, it's simply random; Inheritance happens after this process. Inheritance is basically what color eyes you have, what color and type of hair you have, and others, which are phenotypic. Inheritance is also genotypic, for example the diseases you could (most probably) contract, the mutations you have, whether you're going to be bald in the future, and more. You could also be inherited phenotypic features that your parent's don't seem to have, like blue eyes. One of your parents could be a carrier of the gene, and pass it down to you in a way that it would become phenotypic in you. What a baby is and becomes, is all inherited from both parents, when their DNA combine. The bottom images explain genetic inheritance in a visual way.


Vorzimmer, P. (1963). Charles Darwin and blending inheritance. Isis, 54(3), 371-390.