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DNA 8: Ancient Hominins — How Different Were the Sexes?

A ten‑minute look at body‑size dimorphism from Australopithecus afarensis to later Homo, showing what skeletal evidence can and cannot reveal.

Chapters

0:07 What Is Dimorphism?
1:25 Australopithecus afarensis – Early Hominin Dimorphism
3:10 Later Homo – Growing Differences
5:31 Limits of the Bones and the Way Forward

On-screen text

0:07 What Is Dimorphism?
0:14 What Is Dimorphism?
0:31 Lucy’s femur: 335 mm Historical record · Lucy (A.L. 288‑1) skeleton, National Museum of Ethiopia, 1974
0:49 A.L. 333 pelvis shows female traits Historical record · A.L. 333 partial skeleton, Hadar, Ethiopia, 1975
1:16 A. afarensis femur ratio ≈ 1.13 The Institute's interpretation · McHenry, 1992, Journal of Human Evolution
1:25 Australopithecus afarensis – Early Hominin Dimorphism
1:32 Australopithecus afarensis – Early Hominin Dimorphism
1:49 Lucy ≈ 29 kg The Institute's interpretation · Ruff et al., 1997, Journal of Human Evolution
2:07 Male A. afarensis ≈ 35 kg The Institute's interpretation · Ruff et al., 1997, Journal of Human Evolution
2:25 A. afarensis dimorphism ≈ 1.15 The Institute's interpretation · Wood, 2015, Paleoanthropology
2:43 Robusticity shows activity, not just sex The Institute's interpretation · Ruff, 2002, Annual Review of Anthropology
3:01 Pelvis better for sexing than femur The Institute's interpretation · Lovejoy et al., 2009, Journal of Human Evolution
3:10 Later Homo – Growing Differences
3:17 Later Homo – Growing Differences
3:34 H. habilis femur: 380 mm Historical record · KSD‑VP‑1/1 femur, Koobi Fora, Kenya, 1985
3:52 H. erectus femur: 460 mm Historical record · Zhoukoudian 1 (Peking Man) femur, 1929
4:10 H. erectus femur ratio ≈ 1.20 The Institute's interpretation · Antón & Swisher, 1990, Journal of Human Evolution
4:28 Neanderthal femur: 460 mm Historical record · La Chapelle‑aux‑Saints 1 femur, France, 1908
4:46 Neanderthal dimorphism ≈ 1.18 The Institute's interpretation · Trinkaus, 1994, Journal of Human Evolution
5:04 Modern human femur: 460 mm Historical record · Qafzeh 9 femur, Israel, 1970s
5:22 Modern human dimorphism ≈ 1.05 The Institute's interpretation · Searle & McKie, 1998, American Journal of Physical Anthropology
5:31 Limits of the Bones and the Way Forward
5:46 Bone robusticity reflects activity and sex The Institute's interpretation · Ruff, 2002, Annual Review of Anthropology
6:10 Pelvic shape better indicates sex The Institute's interpretation · Lovejoy et al., 2009, Journal of Human Evolution
6:35 DNA shows male via Y‑chromosome Historical record · Prüfer et al., 2014, Nature (Neanderthal genome)

Sources

Historical record: Lucy (A.L. 288‑1) skeleton, National Museum of Ethiopia, 1974 · A.L. 333 partial skeleton, Hadar, Ethiopia, 1975 · A.L. 438‑1 (male) femur, Hadar, Ethiopia, 1975 · KSD‑VP‑1/1 femur, Koobi Fora, Kenya, 1985 · Zhoukoudian 1 (Peking Man) femur, 1929 · La Chapelle‑aux‑Saints 1 femur, France, 1908 · Qafzeh 9 femur, Israel, 1970s · Prüfer et al., 2014, Nature (Neanderthal genome)

The Institute's interpretation: McHenry, 1992, Journal of Human Evolution · Ruff et al., 1997, Journal of Human Evolution · Wood, 2015, Paleoanthropology · Ruff, 2002, Annual Review of Anthropology · Lovejoy et al., 2009, Journal of Human Evolution · Antón & Swisher, 1990, Journal of Human Evolution · Trinkaus, 1994, Journal of Human Evolution · Searle & McKie, 1998, American Journal of Physical Anthropology

Sound: synthesized ambient (wind, drone, water) (CC0 — made by SoapBox). Made in 70 s of CPU.

Scenes Hathor has no parts for yet (19) — the next things to make

Reconstruction of A.L. 333 pelvis rotating to highlight the sciatic notch.
Side‑by‑side comparison of Lucy’s femur and A.L. 438‑1 femur.
Side‑by‑side comparison of Lucy’s femur and A.L. 438‑1 femur.
Silhouette of Lucy with a weight scale graphic.
Silhouette of Lucy with a weight scale graphic.
Equation graphic showing dimorphism index calculation.
Equation graphic showing dimorphism index calculation.
Animated cross‑section of a femur highlighting cortical thickness.
Animated cross‑section of a femur highlighting cortical thickness.
Side‑by‑side 3‑D models of male and female pelvises rotating.
Side‑by‑side 3‑D models of male and female pelvises rotating.
3‑D rendering of the KSD‑VP‑1/1 femur rotating.
3‑D rendering of the KSD‑VP‑1/1 femur rotating.
Side‑by‑side silhouettes of male and female H. erectus with length bars.
Animated cross‑section of a femur highlighting cortical thickness.
The camera glides over the pelvic inlet, focusing on the broad, oval opening that distinguishes female morphology.
Researchers compare bone measurement charts on tablets, overlaying femur robustness data with pelvic dimensions, discussing uncertainties.
A montage shows varied hominin skeletons, some robust, some gracile, with translucent pelvic diagrams superimposed, illustrating diversity.
Evening shadows fall on the mountain altar where ancient carvings depict towering male figures, firelight dancing on stone.