costs & benefits of ground living. costs & benefits major benefit – tree living = safety...
TRANSCRIPT
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=K8c9lemvciI