This is part one of a two part blog entry. Please see The Evolution of Hominini ~ Part Two here!
As part of my Big History class with a local homeschool co-op, I taught a class about hominini (hominins, or what we used to call hominids) from Australopithecus to Homo sapiens. In case you are curious about the usage of hominin vs. hominid, here is a great explanation!
The class was great fun, and we were very fortunate to have a particular educational resource from The Smithsonian Human Origins program. Last year, The Smithsonian exhibit visited our public library and left a gift of laser printed hominin skulls to be used for education. I checked the skulls out and ....well, it was a gleeful time! Only other anthropology geeks will understand why this is so exciting! :D
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| Using the wonderful DK book, Evolution: the Human Story to show the kids what the hominins might have looked like! |
I only have one hour with my homeschool co-op class, so sometimes it feels like I'm crunching a lot into a short time. As it was, the kids were able to take measurements of the skulls and draw conclusions from those measurements by comparing them.
Some basic trends are that hominin skulls (the cranium) get larger over time. The jaw and teeth get smaller. The foramen magnum (hole where spine goes into the skull) moves from back to center bottom. The nasal openings get smaller, and jaws move under the skull as the frontal cortex becomes larger. We know about these trends, but when you actually measure the skulls of hominins through time, you can see the trends as well as feel them with your hands! This is why I love hands on work.
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| A skunk skull (modern), Australopithecus skull, and modern Homo sapiens skull. Compare the position of the foramen mangum (where the brain stem exits the skull). In the skunk, it is located toward the back of the skull, as its head is thrust forward like a typical quadruped. The Australopithecus (Taung Child) foramen is moving below, and by the time we get to modern humans (and in fact well before) the foramen is centered directly under the skull. This is the trait of upright walkers or bipedal hominins! |
We used calipers to measure the skulls. As always, being on a budget means I'm creative. I found a template for making cardboard (or cereal box) calipers that worked wonderfully. And then the kids got to keep their calipers since they were so easy to make and were plenty.
Here is a link for the cardboard calipers. These work great!
Here is a link for the cardboard calipers. These work great!
I used the wonderful DK Publishers book, Evolution ~ the Human Story, to show the kids what each hominin might have looked like in real life. It's so hard to understand when looking at bones. The eyes and delightful expressions in the models' photos really bring them to life, and tap into the kids' interest.
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| Australopithecus compared to a modern Homo sapiens. The jaw (upper maxilla) becomes much smaller over time, and retreats under the enlarging frontal cortex (forehead). You can see how the brow ridge shrinks and also retreats under the frontal cortex, and how much larger the cranium becomes. Just a few million years of evolution... |
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| These are the lovely Smithsonian Human Origins skulls that I was able to check out from the library. They are laser printed, although they are very nice and accurate models. Each one is a near replica of its real fossil. From left to right: Australopithecus africanus (Taung Child), Homo rudolphensis (similar to H habilus or 'Handy Man'), Homo erectus (one of whom is known as 'Java Man' and is related to H. ergaster or 'Turkana Boy"), Homo heidelbergensis (Heidelberg Man) who is a predecessor to Neanderthal, and finally a modern Homo sapiens (this one is Fish Hoek). Seriously, I can't get over what an amazing resource these skulls are! |
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| We are still all unfolding in this universe! And feeling a bit silly. |
In the next post, I will show more information about each hominin skull, how we charted the measurements, and what we concluded from them.
Here is a nice list of what to measure and what to look for on each skull.
Link For Indiana.edu skull measurements
© 1999 ENSI (Evolution & the Nature
of Science Institutes) www.indiana.edu/~ensiweb
This material may
be copied only for noncommercial classroom teaching purposes, and
only if this source is clearly cited.
Martin Nickels
1. Work in groups of 3-4 students so that everyone can be involved in the activity.
2. BE SURE (!) TO TAKE TURNS doing different measurements and observations.
3. When taking a measurement, use the SLIDING CALIPERS (except for #11 & #12 which may require the HINGE calipers) and remember to...
4. ALWAYS MEASURE IN MILLIMETERS [mm] and round off to whole numbers.
5. PLEASE DO NOT ADD ANY PENCIL OR PEN MARK "TATTOOS" TO THESE CRANIA, OR STICK YOUR FINGERS IN THEIR EYE ORBITS OR NOSES!
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1. Does the FOREHEAD (frontal bone) look more vertical OR flatter when the skull is held in normal anatomical position [NAP] (i.e., with the eyes oriented forward)?
2. Is a SUPRAORBITAL BROWRIDGE present?
3. If present, is the BROWRIDGE DIVIDED in the middle, or CONTINUOUS?
4. What is the SHAPE OF THE BRAINCASE (front to back) when viewed from above?
5. Is a SAGITTAL CREST present?
6. In NAP, is the FORAMEN MAGNUM oriented more downward OR more to the rear?
7. Is the MASTOID process relatively flat OR does it noticeably protrude (project)?
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8. Are the NASAL BONES raised (arched) OR flat?
9. Measure the MAXIMUM BREADTH (width) of the NASAL OPENING [mm].
10. Measure the MAXIMUM HEIGHT of the NASAL OPENING [mm].
11. Measure the LENGTH of the MAXILLA (the upper jaw) [mm]. (Measure down the middle of the palate from the front edge of the foramen magnum to either between or just in front of the two central incisors to determine how much the face projects forward.)
12. Measure the BIZYGOMATIC BREADTH using the hinge caliper if necessary [mm]. (This is the width or breadth of the face from the widest part of one zygomatic arch to the widest part of the other zygomatic arch.)
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13. SHAPE OF THE DENTAL ARCADE: Do the tooth rows diverge towards the back OR are they more straight-sided and parallel to one another?
14. When viewed from the side, are the INCISORS angled out OR are they vertical?
15. Measure the COMBINED WIDTH or BREADTH of the 4 INCISORS together.
16. Does the CANINE tooth project above the chewing surfaces of the other teeth?
17. Is a CANINE DIASTEMA present?
18. Measure the COMBINED LENGTH of the LEFT 2 PREMOLARS and 3 MOLARS together by measuring from the back of the last molar to the front of the first premolar to determine the length of the chewing surface of the "cheek teeth". [mm]. (NOTE: Measure the right side if the left side is missing any of these 5 teeth.)
Read about Evolution of the Hominini ~ Part Two here.
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