ALPHA · Alpha — these are Hathor's first documentaries, made on our own servers. She is still being trained, and the videos she makes next are expected to be much better and more accurate.

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DNA 3: Recombination, Common Ancestors and Heterosis

How chromosome shuffling creates new gene combos, why ancestry tests pinpoint recent common ancestors, and why mixed populations show hybrid vigor and mask recessive traits.

Chapters

0:07 The Shuffling of Chromosomes
1:34 Tracing Recent Common Ancestors
3:01 Hybrid Vigor in Mixed Populations
5:23 Hidden Recessives and Genetic Health

On-screen text

0:07 The Shuffling of Chromosomes
0:14 The Shuffling of Chromosomes
0:31 DNA double helix discovered Historical record · Watson and Crick (1953) Nature
0:49 First genetic map shows crossing over Historical record · Sturtevant (1913) Genetics
1:07 Recombination creates new allele combos The Institute's interpretation · Haldane (1932) Journal of Genetics
1:25 Recombination breaks linkage Historical record · Muller (1932) Genetics
1:34 Tracing Recent Common Ancestors
1:41 Tracing Recent Common Ancestors
1:58 European MRCA ~1500 years ago Historical record · Ralph and Coop (2013) PLoS Genetics
2:16 DNA tests find recent ancestors Historical record · Cavalli‑Sforza, Piazza & Menozzi (1994) Science
2:34 Shared haplotypes reveal MRCA The Institute's interpretation · Baharian and Halperin (2020) Nature Reviews Genetics
2:52 Pedigree collapse creates recent ancestors The Institute's interpretation · Barbujani et al. (1995) Nature
3:01 Hybrid Vigor in Mixed Populations
3:08 Midwest dairy farm, United States, 1930s
3:29 Cross‑breeding dairy cattle raised milk yields (Lush 1937) Historical record · Lush (1937) Animal Breeding Plans
4:06 Dominance & overdominance drive vigor Historical record · Falconer & Mackay (1996) Introduction to Quantitative Genetics
4:29 Hybrid traits not simple averages (Wright 1931) The Institute's interpretation · Wright (1931) Evolution in Mendelian Populations
5:23 Hidden Recessives and Genetic Health
5:30 Hidden Recessives and Genetic Health
5:47 Mendel’s peas hide recessives Historical record · Mendel (1866) Experiments on Plant Hybridization
6:05 Hidden deleterious alleles persist Historical record · Fisher (1918) The Correlation Between Relatives on the Supposition of Mendelian Inheritance
6:23 Bottlenecks reveal recessives The Institute's interpretation · Keller and Miller (2006) American Journal of Human Genetics

Sources

Historical record: Watson and Crick (1953) Nature · Sturtevant (1913) Genetics · Muller (1932) Genetics · Ralph and Coop (2013) PLoS Genetics · Cavalli‑Sforza, Piazza & Menozzi (1994) Science · Lush (1937) Animal Breeding Plans · Falconer & Mackay (1996) Introduction to Quantitative Genetics · Mendel (1866) Experiments on Plant Hybridization · Fisher (1918) The Correlation Between Relatives on the Supposition of Mendelian Inheritance

The Institute's interpretation: Haldane (1932) Journal of Genetics · Baharian and Halperin (2020) Nature Reviews Genetics · Barbujani et al. (1995) Nature · Wright (1931) Evolution in Mendelian Populations · Keller and Miller (2006) American Journal of Human Genetics

Sound: synthesized ambient (wind, drone, water) (CC0 — made by SoapBox). Made in 65 s of CPU.

Scenes Hathor has no parts for yet (10) — the next things to make

1930s university lecture hall, a professor sketching recombination on a chalkboard.
1930s genetics lab, bacterial cultures being mixed on glass slides.
1930s genetics lab, bacterial cultures being mixed on glass slides.
1500s European marketplace, multiple families intermarrying.
1500s European marketplace, multiple families intermarrying.
The farmer guides the two cows into a modest barn, where a calf is born, its coat a mottled blend of both parents.
Colorful beads representing alleles tumble on a wooden table, forming paired combinations that illustrate dominance masking and heterozygote advantage.
A chalkboard sketch shows two genetic models: one where a dominant allele hides a harmful recessive, another where the heterozygote displays superior trait.
The sun sets over the mixed herd on rolling hills, the farmer standing on a ridge, contemplating future generations.
1860s garden, a monk examining pea pods of different colors.