Bipedalism and Tool Making - alejoberrio.comalejoberrio.com/02 discussion Bio346.pdf · Bipedalism...

Bipedalism and Tool Making And the fascinating history of the

extended phenotype

What exactly does it mean for big toes to be abductible (opposable)?

• I was wondering how scientists were able to distinguish oldowan stone tools from just rocks that were formed via natural events. The oldowan stone tools weren't very defined so how can such a clear distinction be made

• what other possibilities for selective pressures other than advantages of gathering food may have selected for bipedalism?

• The Lovejoy article implies that bidepdalism developed primarily because of the new reproductive scheme in that it "freed the hands and made it possible for the male to carry food gathered far from his mate." Which is it more contributed to though, the fact of the cooling, changing climate or the changing into lasting monogamous relationships as the article suggests?

• Does an ectomorph imply the person is less adept for bipedal walking because they do not have as defined muscles?

• How should the different stress patterns placed on the femoral necks of humans and chimps be reflected in the distribution of bone tissue as seen in cross sections? If we could discuss a little bit the differences between the stresses placed on the femoral neck of both chimps and humans I think it would be helpful.

• In the Kivell reading he seems to go back and forth regarding whether MH2 was well-suited for climbing or for stone tool production. I know he is probably just presenting different pieces of evidence related to bone structure but I just want to be clear on the general idea. It says on the 2nd to last page "...Au. sediba still regularly engaged in arboreal behavior. Thus Au. sediba does not have all the morphological features commonly considered necessary to demonstrate a clear commitment to stone tool production." So if a question on the test asked us whether H. habilis or Au. sediba was connected with the first producers of stone tools would we say H. habilis?

• Does the spinal cord go through the foramen magnum? • Can you explain the gluteus muscles vs. gravity slide? In chapter 5, slide 8/35 • Can you explain the breadth/length ratio of head of first metacarpal bone? slide

34/35 in chapter 5 • How does the overall stress pattern imposed on the femoral neck of a chimp differ

from that of the human, and why?

Australopithecus afarensis Homo erectus

Habitual bipedalism in more detail: adaptations of the axial skeleton

Walking can be a pain. Bipedalism leaves the human body vulnerable to a range of problems…

Is it Maladaptive?

Habitual bipedalism in more detail: adaptations of the axial skeleton

• Foramen magnum beneath cranium

– Allows skull to orient forward rather than up

• Enlarged lumbar vertebrae

– Allows them to bear more weight from upright body

• Two added curves in spinal column

– One in cervical vertebrae (neck)

– The other in the lumbosacral vertebrae (lower back to pelvis)

– Results in an S-shaped spine, in contrast to the C-shaped spine of a quadruped

– Positions upper body directly above feet

Habitual bipedalism in more detail: adaptations of the leg and foot

• Femur angled from hip to knee – The knee “valgus angle” – Centers weight over one foot while

other in motion

• Groove for patella (knee cap) is deepened – Prevents dislocation of knee cap

• Arched foot – Aborbs shock

• Short toes (phalanges) improve weight bearing

• In more advanced bipeds, like Homo erectus (perhaps H. habilis) and later – Toe in line with foot – Legs get longer, to allow longer strides

Habitual bipedalism in more detail: adaptations of the leg and foot

• Femur angled from hip to knee – The knee “valgus angle” – Centers weight over one foot while

other in motion

• Groove for patella (knee cap) is deepened – Prevents dislocation of knee cap

• Arched foot – Aborbs shock

• Short toes (phalanges) improve weight bearing

• In more advanced bipeds, like Homo erectus (perhaps H. habilis) and later – Toe in line with foot – Legs get longer, to allow longer strides

Habitual bipedalism in more detail: adaptations of the leg and foot

• Femur angled from hip to knee – The knee “valgus angle” – Centers weight over one foot while

other in motion

• Groove for patella (knee cap) is deepened – Prevents dislocation of knee cap

• Arched foot – Aborbs shock

• Short toes (phalanges) improve weight bearing

• In more advanced bipeds, like Homo erectus (perhaps H. habilis) and later – Toe in line with foot – Legs get longer, to allow longer strides

Habitual bipedalism in more detail: adaptations of the pelvis

• Bowl-shaped pelvis – Hold internal organs from upright body

• Ilium is shortened – Center of gravity closer to hip joint

• Ilium is rotated – Allows insertion of gluteal muscles so

that they can maintain balance – Gluteus minimum and gluteus medius go

from extending the femur in quadruped primates to functioning as abductors • Hold body upright when on one limb • Gluteus maximus continues to function as

leg extensor in bipedal and quadrupedal primates.

• Women have wider hips needed for child birth – Male preferences for swaying hips

speculated to have been exaggerated by sexual selection

Habitual bipedalism in more detail: adaptations of the pelvis

• Bowl-shaped pelvis – Hold internal organs from upright body

• Ilium is shortened – Center of gravity closer to hip joint

• Ilium is rotated – Allows insertion of gluteal muscles so

that they can maintain balance – Gluteus minimum and gluteus medius go

from extending the femur in quadruped primates to functioning as abductors • Hold body upright when on one limb • Gluteus maximus continues to function as

leg extensor in bipedal and quadrupedal primates.

• Women have wider hips needed for child birth – Male preferences for swaying hips

speculated to have been exaggerated by sexual selection

Now, you all should be able to answer: Which features indicate that Australopithecines were habitually bipedal in pelvis, femoral neck, tibia, and leg length?

The Evolution of Hand

The appearance of the human hand features Homo habilis-Homo sapiens common ancestor

Hominins evolved three muscles that flex the thumb: -Flexor pollicis longus -Flexor pollicis brevis -1st volar interosseus of Henle (80% of individuals present a pollical palmar interosseous muscle (of the thumb) as suggested by Henle's description in 1858)

Mousterian Industry:

Oldowan industry:

Acheulean Industry:

Levallois Industry

Silicon Valley Industry

What strikes you about this figure?

well-developed flexor pollicis longus (FPL) muscle?

Precision grip in Australopithecus sediba?

Presence of a projecting sesamoid beak... Similar to modern humans

1st Metacarpal bone

What is meant by “Mosaic Evolution”?

Homo habilis developed the hammer percussion technique, maybe like Kanzi does!

https://www.youtube.com/watch?v=HtoqLZ5XhQ8

The Extended Phenotype

Paleolithic Tools Oldowan Industry 2.6 to 1.2 Mya produced by Homo habilis

Paleolithic Tools Oldowan stone tools were made mostly from lava and chert (a fine-aggregate of silica)

Paleolithic Tools Oldowan stone tools were made mostly from lava and chert (a fine-aggregate of silica)

Paleolithic Tools Acheulean Industry occurred in Saint-Acheul (France) 1.6 to 0.1 Mya

Paleolithic Tools Homo erectus created larger tools with a higher degree of craftmanship. They were made from Flint and they were trimmed bifacially. These tools may be used for chopping and cutting wood, slicing animal hide, defleshing bones, cutting bones and as a weapon.

Paleolithic Tools Homo erectus created larger tools with a higher degree of craftsmanship. They were made from Flint and they were trimmed bifacially.

http://www.hhmi.org/biointeractive/evolution/flintknapping.html

Paleolithic Tools Levalloisian Industry was created by Homo heidelbergensis, the first stone tools were found in Levallois-Perret (suburb of Paris in France), 350 to 100 Kya.

Paleolithic Tools Homo heidelbergensis created this technique for creating sharper tools.

Paleolithic Tools Mousterian Industry was created by Homo neanderthalensis, their first stone tools were found in Le Mounster in Peyzac-le-Moustier, Dordogne, France. They were made between 200 Kya to 30 Kya

Paleolithic Tools Mousterian Industry is characterized for being more diverse than the previous industries. The flakes were also processed and used for specials uses.

Upper Paleolithic Tools They have been found worldwide, many different uses and materials. The most interesting ones are known as spear-throwers. From 50 Kya to 10 Kya (today). Modern Homo sapiens.

Upper Paleolithic Tools In the upper paleolithic we also use an exceptional use of art.

From the Upper Paleolithic to the present