Synapsid & Mammal Evolution
Early Complex Sentience Emerges: Dimetrodon
295 Million BCE
Complex Brains; Long-Term Memory; Early Complex Sentience.
XX/XY Sex System Emerges: A Tale of Mammalian Evolution
240 Million Years Ago
Platypus–Ape Common Ancestor
225 million years ago (±5 million years)
When dinosaurs rose, our line quietly began.
Morganucodon: An Early Mammalian
203 Million BCE (+/- 3 million)
Differentiated teeth and true mammalian jaw
Early Play Evolves in Mammals
190 Million Years Ago (+/- 10 million years)
Parental care, brain plasticity, extended juvenile period
Mammals: First Live Births
185 Million BCE
Placental nutrient transfer (in placentals)
Complex Sentience Settles: Eomaia scansoria
circa 125 Million BCE
Complex Brains; Long-Term Memory; Complex Sentience; Likely Proto Self-aware.
Animal Vocabulary: Dozens of Words
125 Million Years Ago
Expanded Limbic System, reward circuitry
Appendix
80 Million BCE
Higher Play Evolves in Social Mammals
80 Million Years Ago (+/- 10 million years)
Enlarged neocortex
Purgatorius — Earliest known proto-primate.
66 Million BCE
Grasping hand and flexible ankles
Opposable Thumb Emerges
60 Million Years Ago
Plesiadapis: First fruit-insect eaters.
56 Million BCE (+/- 2 million)
Enhanced color perception, Diet-driven brain growth
Early Self-Awareness: Miacis
50 Million BCE
Territory memory, where things are, hippocampus development
Ape Thumb Evolves
32 Million Years Ago (+/- 2 million)
Early Intelligence Emerges: Aegyptopithecus zeuxis
30 Million BCE
Complex Brains; Long-Term Memory; Complex Sentience; Semi Self-awareness settles in.
Baboons Branch Off: Old World Monkeys
27 Million Years Ago (+/- 2 million)
Large neocortex, Coalition politics emerge
Genus Proconsul (Self-Awareness Settles)
20 Million Year Ago (+/- 2 Million Years)
Complex Brains; Long-Term Memory; Complex Sentience; Maybe Self-aware; Likely Simple EI.
Gibbons Branch Off: Genus Hylobates
17 Million Years Ago, ± 1 million
Long-distance pair bonding, Fine motor control
Orangutans Branch Off: Genus Sivapithecus
Emerged 12.5 to 12 mya, extinct 8.5 to 7 mya.
Complex Brains; Long-Term Memory; Complex Sentience; Self-aware; Complex EI.
Gorillas Branch Off: Genus Nakalipithecus
Emerged 10 mya, extinct 9.8 to 9 mya.
Ancestral Hominids (us, pre-split)
Emergence of the Chimpanzee Family
2 Million BCE
Hominids, Not Us (different branch)
Genus Orangutans
400,000 Years Ago