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Primate Development
What makes primates different from other mammals, and why did those differences matter?

Welcome to the primate family! Your learner will discover that humans are primates (just like monkeys, apes, and lemurs) and that all primates share a common ancestor from millions of years ago. This lesson explores the special traits that make primates distinctive: grasping hands, forward-facing eyes, and large brains. It's a humbling and exciting realization that humans are part of a much larger family tree, and understanding our primate heritage helps us understand ourselves.

S2S_Lesson28 by Selene

Key Ideas

  • Humans belong to the primate group and share ancestry with other primates. They are not descent from modern apes.
  • Shared primate traits include grasping hands, opposable thumbs, binocular vision, and larger brains.
  • Evolution causes populations to change gradually over many generations.
  • Different primate lineages adapted to different environments, leading to today's diversity.

Spine
  • Mammoth Science: DNA pg. 74, Evolution pg. 76
✏️  Notebooking Activity
There are two notebooking pages for this lesson. Page 1: Create a chart of primate development. Page 2: List four traits that most primates share.


Cosmic CalendarWhere we are: December 31 · 6:05 PM to 8:00 PM
We are now in the evening hours of December 31st. Read the script below before the lesson.

Read aloud: We’re deep into the evening of December 31st now on our Cosmic Calendar. Six o’clock in the evening on the last day of the cosmic year. At around 6:05 PM, apes appear. At around 8:00 PM, the line that will lead to hominids branches off. In real time, apes go back about 28 million years, and the earliest hominids appear around 12 million years ago. Six in the evening. That’s how recent our family line is. Most of this calendar year was filled with life that had no connection to us at all. We are late arrivals, and our branch of the tree is very young. Midnight is getting close. Watch those hands.

Timeline EntriesLabel the next page in your timeline “Primate Development: 15 Million Years Ago”. The workbook prompt asks learners to draw several Miocene primates in the trees, making sure to show their grasping hands, forward-facing eyes, and one coming down to the ground on two legs.

Discussion Questions
  1. What animals are primates? 
    Sample answer: Humans, monkeys, apes, and lemurs are primates.
  2. What body parts do many primates have in common?Sample answer: Hands for grabbing and eyes that face forward.
  3. Why is it helpful for primates to have hands instead of paws? 
    Sample answer: Hands help them grab food, climb, and use tools.
  4. How do primate traits help with survival? 
    Sample answer: Grasping hands help with climbing and feeding, and forward-facing eyes help with depth perception.
Digging Deeper
  • What does it mean to share a common ancestor
    Sample answer: It means different species came from the same population long ago.
  • Why don't humans "come from" modern apes? 
    Sample answer: Humans and apes evolved separately from a shared ancestor.

Vocabulary
  • Primate — A group of mammals including monkeys, apes, lemurs, and humans; characterized by grasping hands, forward-facing eyes, and large brains.
  • Opposable Thumb — A thumb that can press against the other fingers, allowing precise gripping; a key primate trait.
  • Binocular Vision — The ability to see a single image with both eyes, providing depth perception; essential for judging distances.
  • Common Ancestor — A species that two or more groups of organisms descended from; humans share a common ancestor with other apes.
  • Species — A group of organisms that can interbreed and produce fertile offspring.
  • Evolution — The change in inherited characteristics of populations over generations; primate evolution produced enormous diversity.
  • Arboreal — Living in or adapted to life in trees; early primates were arboreal, which drove the evolution of grasping hands.

Species to ResearchThis lesson covers primate development and early apes. Here are some species learners can choose to research:
  • Aegyptopithecus— An early primate ancestor from Eocene Egypt; one of the oldest known relatives of both monkeys and apes.
  • Proconsul— An early Miocene ape from Africa; it lacked a tail and is considered a transitional form between monkeys and apes.
  • Gigantopithecus— The largest ape that ever lived; it stood up to 3 meters tall and lived in Asia until about 100,000 years ago.
  • Ardipithecus ramidus— A very early hominin from Ethiopia, about 4.4 million years old; it could walk upright but also climb trees.
  • Australopithecus afarensis— Known from the famous fossil “Lucy”; a bipedal hominin that lived in Africa about 3.2 million years ago.

SCIENTIST SPOTLIGHT: Jane GoodallJane Goodall is a British primatologist and conservationist who, beginning in 1960, spent decades living alongside wild chimpanzees in Gombe, Tanzania. Her observations overturned fundamental assumptions about what made humans unique. She documented chimpanzees making and using tools, something that scientists had believed only humans could do. She observed complex social relationships, emotions, and even violence among chimps. Her methods were initially criticized by the scientific establishment, partly because she gave the chimpanzees names rather than numbers. She was largely self-taught when she began her work, sent to Africa by the paleontologist Louis Leakey, who believed that patience and fresh eyes mattered more than formal training. She has spent the decades since advocating for conservation and taking her message to schools around the world.

Books:
Videos:
Digging Deeper Activity:
What specific behaviors did Goodall observe in chimpanzees that changed how scientists understood the boundary between humans and other primates? Research one behavior, such as tool use, communication, or social structure, and compare what chimpanzees do to what humans do. What does the similarity suggest about our shared evolutionary history?

Sources

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