1. GRADE 8 SCIENCE NAREEFA N. BACCHUS
EVOLUTION
GRADE 8 SCIENCE
NAREEFA N. BACCHUS

2. WHAT IS EVOLUTION? Simply put, evolution is change.
A species is a group of organisms that share similar characteristics and can reproduce among themselves to produce a fertile offspring.
Many characteristics of a species are inherited by the offspring from their parents.
Changes in these inherited characteristics over time is evolution.

3. Jean Baptiste De Lamarck
Jean Baptiste de Lamarck proposed a hypothesis that explains how species changes over time. He suggested that characteristics or traits were changed because of what an organism learns throughout its lifetime.
Lamarck believed that organisms can learn from their environment and makes changes to help them in their lifetime, then pass it on to their offspring.

4. VIDEO ON CHARLES DARWIN: THE FATHER OF EVOLUTION.

5. Charles Darwin Charles Darwin is an evolution scientist.
He loved recording observation of various plants and animals. He was fascinated by the variety of life on the Galápagos islands.
He assumed that the plants he saw must’ve come from central and south America yet the Galapagos had plants never seen in south America.

6. What Darwin really studied!
In the Galapagos islands, Darwin observed and studied 13 species of finches.
Finches are a type of bird.
He noticed that all 13 species were generally similar except with respect to their body size, beak shape, and eating habits. He also noticed that the Galapagos finches were similar to a species he’d seen back in south America.
Darwin then came to the conclusion that maybe there was competition for food so the birds competed, and as a result, they were different sizes.

7. NATURAL SELECTION
This is a theory by Charles Darwin. He believes that natural selection is the main process responsible for evolution.
Natural Selection means that the organism with traits best suited to their environment and aids in their survival are more likely to be survive and reproduce. These traits are then passed on to the offspring.

8. VARIATION AND ADAPTATION
The difference between individuals of a species is known as VARIATION.
A VARIATION IS AN INHERITED TRAIT THAT MAKES AN INDIVIDUAL DIFFERENT FROM OTHER MEMBERS OF ITS SPECIES. VARIATION RESULTS FROM PERMANENT CHANGES OR MUTATIONS IN AN ORGANISM’S DNA.
Some variations are more helpful than others. In other words the mutation that causes the change may be beneficial or harmful.
An adaptation is any variation that makes an organism better suited to its environment. (So, its basically a good change).
Variations that result in adaptation can involve an organisms color, shape, behavior, or chemical make up. For example, being camouflage is a good variation to have. It is an adaptation that will help an organism to blend into its environment and make it less obvious to predators. So, being camouflage increases the chance of survival and the chance to live on and reproduce.
On the other hand, Albinisms is a variation that doesn't’t help with adaptation as it causes an organism to stick out like a sore thumb. It makes the organism more noticeable and more obvious to its predators.

9. THE PEPPERED MOTH

10. THE SPEED OF EVOLUTION
Scientists cannot agree on how quickly evolution occurs. Many scientists believe that evolution occurs slowly or gradually, over a long period of time such as tens or hundreds of millions of years.
On the other hand, some scientists believe that evolution is a quick process.
In other words, scientists can’t seem to agree with each other on this issue. Shocker right?

11. THE SPEED OF EVOLUTION
In general, the slower the reproduction rate, the slower the rate of evolution. The faster the reproduction rate the faster the rate of evolution.

12. CLUES ABOUT EVOLUTION FROM FOSSILS
Paleontologists are scientists who study the past by collecting and examining fossils.
Fossils are the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.

13. CLUES ABOUT EVOLUTION FROM FOSSILS

14. FOSSILS Most fossils are found in sedimentary rocks.
The fossil record provides evidence that living things have evolved or changes from how their ancestors once were.

15. TWO BASIC METHODS FOR DATING FOSSILS
1. RELATIVE DATING (LESS ACCURATE): the relative date/ age of a fossil cane be estimated from the ages of rocks in nearby layers.
2. RADIOMETRIC DATING (MORE ACCURATE): this method utilizes radioactive elements from the periodic table to determine the age of fossils by using the concept of half-life.
Look at the video as it’ll help you to better understand the technique of radiometric dating.

16. FOSSILS AND EVOLUTION
Older fossils are in the deeper layers and newer fossils are on the upper layers (i.e. Closer to the surface).

17. MORE CLUES ABOUT EVOLUTION
1. EMBRYOLOGY: there are differences in the way organisms develop during their embryonic phase.
2. HOMOLOGOUS STRUCTURES: these are body parts that are similar in structure and function. This often indicates that 2 or more species share a common ancestor.
3. VESTIGIAL STRUCTURES: these are structures that are present, but do not seem to have a function. Maybe it once served a purpose in the ancestors, but within the current organism, they serve no purpose.
4. DNA: Scientists compare DNA from living and dead organisms to identify similarities among species of the past and present.

18. Believe it or not, I dreaded teaching this chapter more than I did the reproductive one, only because I wanted to do a good job of relaying the message while not confusing you at the same time.
I don’t usually feel the need to bring religion into science or vice versa. However, for this topic, I feel the need to clarify a few things. We did not become the beings we are because we were derived from monkeys. Is it possible that we share similarities to other primates? Sure. But just like Adam and Isa’s miraculous births in their own respects, humans are a miraculous creation.
I think perspective is key when studying evolution. It is important to understand that organisms didn't come to be just on their own, nor did they evolve and change at their own will. There is a greater power that is responsible for these phenomenon, Allah.
We’ll talk more in class. Ciao!

19. My point exactly,
Nuff’ Said.