Natural Parenting
by Jeff
Image text: On one hand, every single one of my ancestors going back billions of years has managed to figured it out. On the other hand, that's the mother of all sampling biases.
This comic is saying that sex "comes naturally".
Sampling bias is a non-random sample of participants in a study. In this case, all of the participants were self-selected to be parents. And of course there is a pun in "mother of all sampling biases".
Conversations
by Mike
Image Text: If the dysentery graph looks historically inaccurate it's because I got all my data from Oregon Trail.
Dysentery is a disease that causes fatal diarrhea. Frequently caused by an infectious bacteria, virus, or parasite, this disease was a common way to die in the computer game Oregon Trail. This comic suggests that it is spread more easily while on the toilet and with the rise in laptop sales (and rise in people are "conversing" over the internet while on the toilet) we will see a new rise in cases of dysentery.
UPDATE: "There are three graphs. It doesn’t imply that “we will see a new rise in cases of dysentery.”, it implies more conversations will take place with someone on the toilet due to using a laptop, when in the past it was due to dysentery." - Thanks Dave!
Date
by Mike
Image Text: Well, the kid's definitely getting the biology geek phenotype.
Punnett squares are simple diagrams used to determine the odds of a particular offspring genotype (genetic make up) given the genotypes of the parents. The phenotype is the physical manifestation of the genes in the organism and doesn't always correlated directly to strict genotypes. Some genetic characteristics (like color blindness and eye color) can be easily traced using Punnett squares because they are the result of one clearly dominant gene and one clearly recessive. Other traits like height are a blend of multiple genes.
An interesting thing to note:
The male's parents were both colorblind but that is a recessive gene on the X chromosome. For his mother to be colorblind she must have had two copies of the gene. This man now carries the gene on his X chromosome so he will only pass it on to his daughter. She will be a carrier but will have normal color vision so long as this woman is not colorblind.