COSTS BENEFITS OF GROUND LIVING COSTS BENEFITS Major
COSTS & BENEFITS OF GROUND LIVING
COSTS & BENEFITS • Major benefit – tree living = safety from predators.
COSTS & BENEFITS • Major benefit – tree living = safety from predators. • Cost – leaves and fruits aren’t as rich in protein or energy.
COSTS & BENEFITS • Major benefit – tree living = safety from predators. • Cost – leaves and fruits aren’t as rich in protein or energy. • Life on ground = wider diet, yet predation risk is greater.
BIPEDALISM EVOLVED QUICKLY • The change from brachiation to bipedalism probably occurred within 2. 5 million years.
BIPEDALISM EVOLVED QUICKLY • The change from brachiation to bipedalism probably occurred within 2. 5 million years. • Extensive changes to hip and leg – fast evolution = strong selective pressure.
CARRYING INFANTS • Infants able to be born earlier and more helpless if carried.
CARRYING INFANTS • Infants able to be born earlier and more helpless if carried. • Human babies can’t grasp fur (as it’s not there) because they don’t have an opposable toe.
CARRYING INFANTS • Infants able to be born earlier and more helpless if carried. • Human babies can’t grasp fur (as it’s not there) because they don’t have an opposable toe. • This adaptation would accelerate quickly – a partially bipedal pre-human would have a big toe facing more directly forward for walking
CARRYING INFANTS • Infants able to be born earlier and more helpless if carried. • Human babies can’t grasp fur (as it’s not there) because they don’t have an opposable toe. • This adaptation would accelerate quickly – a partially bipedal pre-human would have a big toe facing more directly forward for walking = offspring having the same trait = less able to cling on = mother would have to hold onto the baby
CARRYING INFANTS • Infants able to be born earlier and more helpless if carried. • Human babies can’t grasp fur (as it’s not there) because they don’t have an opposable toe. • This adaptation would accelerate quickly – a partially bipedal pre-human would have a big toe facing more directly forward for walking = offspring having the same trait = less able to cling on = mother would have to hold onto the baby = increasing advantage of having a forward facing toe.
CARRYING FOOD • Enabled large food items to be carried back to safety =
CARRYING FOOD • Enabled large food items to be carried back to safety = males could attract mates this way =
CARRYING FOOD • Enabled large food items to be carried back to safety = males could attract mates this way = females then choose the ‘best providers’ for their offspring.
KEEPING COOL • A popular theory – bipedalism evolved in order to avoid getting too hot.
KEEPING COOL • A popular theory – bipedalism evolved in order to avoid getting too hot. • By being upright, a human body absorbs much less heat energy than it would if exposed to the sun on all fours.
KEEPING COOL • A popular theory – bipedalism evolved in order to avoid getting too hot. • By being upright, a human body absorbs much less heat energy than it would if exposed to the sun on all fours. • Hair on heads = reduced heat absorption.
KEEPING COOL • A popular theory – bipedalism evolved in order to avoid getting too hot. • By being upright, a human body absorbs much less heat energy than it would if exposed to the sun on all fours. • Hair on heads = reduced heat absorption. • Raising the body = surrounding air cools it
KEEPING COOL • A popular theory – bipedalism evolved in order to avoid getting too hot. • By being upright, a human body absorbs much less heat energy than it would if exposed to the sun on all fours. • Hair on heads = reduced heat absorption. • Raising the body = surrounding air cools it • This hypothesis links bipedalism with the high density of sweat glands and semi-naked skin.
KEEPING COOL • A popular theory – bipedalism evolved in order to avoid getting too hot. • By being upright, a human body absorbs much less heat energy than it would if exposed to the sun on all fours. • Hair on heads = reduced heat absorption. • Raising the body = surrounding air cools it • This hypothesis links bipedalism with the high density of sweat glands and semi-naked skin. • Overheating could be avoided by staying in shade = less foraging time = less food.
OTHER ADVANTAGES • Predators can be seen earlier when upright
OTHER ADVANTAGES • Predators can be seen earlier when upright • More effective at brandishing weapons
OTHER ADVANTAGES • Predators can be seen earlier when upright • More effective at brandishing weapons • Taller body may seem larger to predators. • https: //www. youtube. com/watch? v=K 8 c 9 lemvci. I
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