How have cell phones changed over time?

Evolution of the Cell Phone

Evolution of Batman

Evolution

• Change over time

The History of Biological Evolution

Historical Thoughts on Evolution

• Aristotle (384-322 BC): derived a concept called Scala Naturae – “Great Chain of Being” or “The Ladder of Life”– Hierarchical chain starting with God & progressing

downward to less complex organisms

• Literal Biblical view: the world was created in 6 days– Earth is 6,000 years old.– All species were created as they are today.

The Development of Modern Views on Evolution

• By the 17th century, scientists had rejected Aristotle’s theory.

• Most scientists accepted that evolution was occurring, they just didn’t know how it was happening.

• In the 1800s, modern theories of evolution began to develop.

• The theory of evolution that we accept as true today was influenced by many fields of study.

Influences from Geology

• Charles Lyell (1833): geological processes occurring now are the same geological processes that shaped Earth’s physical features over long periods of time.– The present is the key to understanding the past.– Influential in Darwin’s work

Influences from Economics/Sociology

• Thomas Malthus (1798): population size linked to poverty & disease

• If the human population continued to grow unchecked (grow exponentially), it will be limited by space & food supply.

Population Growth Chart

• Carrying Capacity: the maximum # of individuals in a population that can be supported by a particular environment

Malthus believed that as the human population neared its carrying capacity, disease, lack of food, etc. would increase & the human

population would steady.

Sea turtles lay hundreds of eggs, but only a few survive.

WHY?

Trees produce hundreds of seeds, how many actually mature?

WHY?

Jean-Baptiste Lamarck (1809)Inheritance of Acquired Traits

• One of the 1st to propose a mechanism to explain why organisms change over time.

• Believed that organisms would gain or lose features if they overused or did not use the traits– If you don’t use it, you lose it!– These traits could be passed on to their

offspring.

Lamarck’s Hypothesis

Organisms would gain or lose features if they overused or did not use the traits, & they could pass these new traits

on to their offspring.

Scientists knew that snakes had probably evolved from lizards. But how?!

Lamarck thought that there was a lizard who didn’t use its legs, so the legs got smaller & smaller.

This lizard’s offspring would be born without legs.

Lamarck’s Hypothesis

• Tendency Toward Perfection– Organisms are continually changing & acquiring features

that help them live more successfully in their environments.

• Use & Disuse– Organisms could alter the size or shape of particular

organs by using their bodies in new ways.

• Inheritance of Acquired Traits– Any changes could be passed down to offspring.

The evolution of Fiddler Crabs according to Lamarck:

Do you agree with Lamarck’s hypothesis?

A. Yes - I agree!B. No - I don’t agree!

WRONG!

Lamarck’s HypothesisNot supported by scientific evidence…

How did his hypothesis positively influence evolutionary thought?

• His hypothesis on evolution was incorrect in several ways.

• BUT he was the 1st to recognize that organisms are well suited to their environment!– Key concept for future work!

Charles Darwin

• In 1831, sailed on the H.M.S. Beagle around the world– Collected plants, animals, fossils, OBSERVED

Darwin’s Observations

Species on the Galapagos Islands were similar to the mainland, but

differ in each environment.

There are several types of finches in the Galapagos. They’re similar to the finches found in Ecuador,

but each is a little different.

Darwin’s Questions About the Finches

Finches differed from island to island. Why?

Did all these species evolve from one species of finch?

How did the finches change over time?

Darwin’s Observations

• Variation exists within a population & some of that variation is inheritable.

Some peppered moths carry the gene for white coloration, but some carry the

gene for black coloration.

Which moths do you think will survive to pass on their genes?

Darwin’s Observations

• Similar habitats around the world don’t have the same animals & plants, but the animals & plants have similar characteristics for that environment.

Capybara

Beaver

Beavers are found in North America, while Capybaras are found in South America.

Both species live in watery environments, & therefore have similar characteristics

(like webbed feet).

Darwin was influenced by Malthus’ work.

• Darwin thought that since plants & animals have more offspring than humans, the “Struggle for Existence” would apply more strongly to plants & animals.

If all finches ate the same type of food, there would be too much competition.

Darwin was also influenced by Lyell’s work.

• Darwin realized that if the Earth could change over time, life itself might change over time in response to physical changes of the Earth & that the changes he proposed would require many, many years.

Darwin’s Theory of Evolution

• 1859: Charles Darwin published On the Origin of Species by Means of Natural Selection

• He believed that populations evolved by a process called natural selection.

Evolution by Natural Selection

• Evidence for this hypothesis has been described in many studies & is well supported.

• Darwin’s original hypothesis is now known as the Scientific Theory of Biological Evolution.

Lamarck vs. Darwin

• Both Darwin’s & Lamarck’s hypotheses support evolution, but they differ in how evolution occurs.

How is Darwin’s theory of evolution different from Lamarck’s hypothesis?

How did elephants get their long trunks?

Put both sets of cards in order, then try to decide whose theory is whose.

Which one is Darwin? Which one is Lamarck?

Darwin or Lamarck?Lamarck!

Darwin or Lamarck?Darwin!

Studies that Support Darwin’s Theory of Natural Selection

• Fossil Record• Population Genetics• Animal Behavior• DNA Fingerprinting• Antibiotic Resistance in

Bacteria

Before you leave…

• On a sheet of paper (share!), write your response to the following:

Thomas Malthus believed that the human population would naturally be kept in check by lack of food, disease, etc.

Do you believe that this is happening to the human population today? Why or why not?