Science & Society
Where these ideas meet everyday life: family history, numbers, patterns, cooperation and the questions people ask about them.
AncestryDNA vs 23andMe for finding relatives: which match list does more
AncestryDNA vs 23andMe for finding relatives: database size, how matches and shared cM are shown, trees, segment tools, privacy and when to test both.
How many ancestors do I have? Counts for 10, 12 and 20 generations
You have 2^n ancestors n generations back and 2^(n+1) - 2 in all: 1,024 at 10 generations, 4,096 at 12, over a million at 20. Why fewer real people fill them.
Small worlds and six degrees: what the folders, the model and the emails showed
Milgram's folders, the Watts and Strogatz rewiring model worked by hand, the 2003 email study, and what six degrees does and does not mean for villages and kin.
What the evidence says about Dunbar's number
Where the 150 in Dunbar's number comes from, the arithmetic behind it, what network studies find, and why a 2021 reanalysis and Dunbar's reply disagree.
Pedigree collapse: why no one has a billion ancestors
Why the doubling of ancestors cannot go on: pedigree collapse worked through with small numbers, the Spanish Habsburgs, and what Chang and Rohde found.