Evolution Lab - Part One Questions.

 
 

 

African Elephants. These are the bigger-eared of the two living species of elephants. What adaptive advantages and possible disadvantages can you see in the following elephant traits?

E-1. Large size. They are the largest living land animals.

E-2. Trunk. Few animals have anything like it.

E-3. Long lives. Elephants are one of the longest-living animals, and don't even hit puberty until their 'teens.

E-4. Tusks. These are huge, very modified teeth.

E-5. Bluff charge. When the group is threatened, the lead male will charge the threat, but will usually stop before actually reaching the threatening animal.


E-6. Gender size differences. Full-grown, males are almost always quite a bit larger than females.



African Lions. These are one of the savannah region's top predators, one of the few cats who live in large groups, or "prides."  Different populations have a different behaviors, but the following has been observed in Serengeti lions.

L-1. Living in groups. Lions live in fairly large, extended family groups, each with one dominant male, several females, and young, from cubs up to mature females and almost mature males.

L-2. Hunting in groups. Small groups of lions hunt together, hiding around a prey herd then "flushing" the herd from one spot.

L-3. Female hunters. The main hunters in any pride are the adult females.

L-4. Male mane. Lions are the only big cats with this feature.

L-5. Baby killing. When a new male takes over a pride by ousting the current male, he drives away the larger youngsters and kill the cubs.

 

Gazelles. These smallish, slender antelopes have long spiral horns, a quick, bounding run, and live in moderate-sized herds. They share many of the traits mentioned here with other types of animals.

G-1. Living in herds. They live together in herds with no real organization - they just hang out together.

G-2. Long necks. Most 4-legged, open-feeding plant eaters have this trait.

G-3. Chaotic flight from danger. When the herd is attacked, gazelles flee in almost every direction. They almost never use their horns to defend the group.

 

Giraffes.

Gi-1. Long neck. Explaining this has been a goal of evolutionists since the beginning.

 

Leopards.

Le-1. Ambush hunters. Leopards work alone - a single leopard will hide and strike quickly from its hiding place.

 

Rhinoceros. African rhinos are the ones with two horns on their noses.

R-1. Head near the ground. Unlike many of the other open-field herbivores, rhinos carry their heads much closer to the ground.

R-2. Great nose, bad eyes. A rhino's sense of smell and hearing are very good; their eyes are pretty poor, very nearsighted.

 

Baboons. These monkeys' tree-dwelling ancestors, like humans' tree-dwelling ape ancestors, adapted to an open savannah existence. Notice how the adaptations listed below are similar to features also found in humans.

B-1. Omnivorous diet. Unlike their largely fruit-and-nut-eating cousins, baboons will eat almost anything but really fibrous plant matter (they can't digest grass or many leaves); their diets consist of some fruits and nuts, but also roots, insects, and meat, scavenged or caught.

B-2. A complicated social order. Members of baboon troops tend to have specific jobs assigned to them, with a definite order of importance or pecking order and a lot of cooperation.

B-3. A reputation for nastiness. A baboon troop will often react to even a mild or potential threat with a coordinated attack meant to maim or kill. One baboon alone is not much threat, but even large predators learn to leave the troops alone.

 

Humans. The adaptations for open-grassland existence appear to have come in roughly the order they're brought up here. Notice that many features could naturally lead to the next one on the list.

Hu-1. Walking on two legs. This means not just being able to, but doing it as a normal method of getting around.

Hu-2. Ability to carry things. With the hands free, things could be carried for long distances.

Hu-3. Making durable, reusable tools. The few other animals that make tools produce the use-once, throw-away kind.

Hu-4. Settled lifestyle. Humans began to work out of established base-camps for fair periods of time.

Hu-5. Classic gender roles. It's usually considered as men being the hunters and defenders, women being the gatherers and family-raisers. Don't assume that the non-sexual physical differences between the genders existed first - they might have, but they probably didn't.

Hu-6. Long term monogamous relationships. This is the "pairing up" within a group, usually for quite long terms, single males with single females or occasionally single males with multiple females.

Hu-7. Females with no obvious fertile periods. Most other animals go into an obvious "in heat" period when fertile; human women's fertile times are well hidden, even from them.

Hu-8. Language. The ability to communicate this way may be a fairly recent development, although the potential ability to understand such communication appears to have been around a long time.


Other things to think about: it is assumed that all traits found in humans have some adaptive advantage, and evolutionary scientists are trying to explain in those terms such human traits as religion, humor, music, and grief. Can you see any general advantages that would lead to these adaptations?


 
     

 

 

First Written 1996;  Last Update 2003;  Web Version 2001,  M. McDarby

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