This detailed Grade 12 IEB Life Sciences summary on evolution covers the theory of natural selection, genetic variation, and evidence supporting evolutionary theory, including fossils, comparative anatomy, and genetic drift. Perfect for students preparing for exams, this guide offers insights into ...
EVOLUTION
The heritable changes in organisms that occur over time resulting in changes within species and
also enabling one species to develop into another, or many other, species over a great deal of time.
Hypothesis vs Theory:
Theory: A widely accepted general explanation for a natural phenomenon based on a body of
evidence including repeated observations and experiments.
Hypothesis: An educated but untested prediction, idea or explanation for observations in the form
of a statement.
The role of scientists in the development of the theory of evolution:
I. Erasmus Darwin
• Grandfather of Charles Darwin , who was a naturalist and formulated one of the !rst
theories on evolution
• He believed:
‣ All organisms descended from a common ancestor
‣ Organisms changed over time
‣ These changes were inherited by their o"spring
‣ However he had no explanation for how this took place
II. Jean Baptiste De Lamarck
• French biologist who proposed “inheritance of acquired characteristics” which presented the
idea that an organism changes during life in order to adapt to its environment and that those
changes would then be passed on to their o"spring [UNTRUE]
• He believed:
‣ One species gives rise to another and that humans arose from another species (similar to E.
Darwin)
‣ Organisms changed to meet the requirements o" their environment
‣ The law of use and disuse - organs that are used a lot develop to become bigger and more
e#cient whereas those not used much disappear.
‣ These organs acquired during the organisms lifetime is passed down to o"spring.
III. Charles Darwin - father of evolution
• Naturalist and biologist known for his theory of evolution and the process of natural
selection (Darwinism)
• De!ned evolution as “descent with modi!cation” the idea that species change over time, give
rise to new species, and later share a common ancestor
• His theory of evolution declared that species survived through a process called ‘natural
selection,’ where those who were successfully suited to meet the changing requirements of
their natural habitat thrived, and those who weren’t, didn’t reproduce and died o".
1
, IV. Alfred Russel Wallace
• Had the revolutionary idea of evolution by natural selection entirely independently of
Charles Darwin.
• Noticed a striking pattern in the distribution of animals around the archipelago. He
proposed an imaginary line dividing the region in two parts (Wallace’s Line), this marked
the boundary between the animal life of the Australian region and that of Asia.
• He came to understand how species evolved - they changed because the !ttest individuals
survived and reproduced, passing their advantageous characteristics on to their o"spring.
2
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller TanyaChigs. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R220,00. You're not tied to anything after your purchase.
