Human Bipedalism: New Science Reveals Why We Walk Upright
Okay, here’s a breakdown of the key information from the text, focusing on the two evolutionary changes related to bipedalism:
1. Change in Cartilage Formation:
What it is: A genetic innovation affecting how cartilage forms in the developing pelvis during embryonic advancement.
Effect on the Ilium: This change caused the ilium (upper pelvic bone) to develop a shorter, wider, and curved shape in humans, compared to the high, flat, and narrow shape seen in other primates.
Benefit: this new shape provided greater stability during upright walking and running.
2. Delayed pelvic Ossification & Backward Displacement:
what it is: A genetic innovation that delayed the process of the pelvis turning into bone (ossification) and shifted where this process began.
Effect: This retained the new, human-like structure of the ilium (from the first innovation).
Benefit: this change facilitated brain growth in human ancestors and allowed women to give birth.
In essence, the text highlights that these two genetic changes working together were crucial for the development of bipedalism and, importantly, also had a positive impact on brain size and childbirth in the human lineage.