Lecture 15 - flores naledi heidelbergensis

homo floresiensis

190,000-50,000 ya

island of flores, indonesia

height: 3ft 6in

400cc

floresiensis discovery

first fossil discovered 2003

liang bua cave

initially thought to be H erectus child or adult with microcephaly

similar sized postcrania later discovered

other floresiensis fossils

more recent discoveries at site mata menge (on flores) date 700,000ya

early form of H floresiensis? → even smaller than later examples

shows similarities to H erectus fossils from java, supports phylogenetic link

floresiensis lifeways

produced oldowan tools

hunted giant rats, maybe small elephants

defended against predators like komodo dragons, alligators

did not use fire

adapted more for walking than running

why were they small

insular island dwarfism: isolated island populations sometimes exhibit reductions in body size over time

• lack of predators

• fewer resrouces

• smaller body sizes selected because they require less energy

same phenomenon occurred in stegodon, tiny elephants on Flores

or descended from smaller-bodied hominin

• habilis or the dmanisi hominins more similar in body size

• some argue that floresiensis brains are proportionally too small to be descendants of H. erectus

• also foot seemingly less adapted to distance running

• idea less supported with new evidence from mata menge and cranial scans suggesting slightly larger brain sizes

floresiensis extinction

occurred around the time H. sapiens arrived on flores ~50,000 ya

genetic drift in small population led to genetic diseases

or competition from H sapiens? no evidence the 2 species interbred

H. heidelbergensis

appeared 800-500kya in zambia

one of several types of middle pleistocene homo (no chin)

possible common ancestor to H. sapiens and H. neanderthalensis

H. heidelbergensis traits

morphology (ancestral): massive brow ridges

derived: cranium = 1280cc, rounded occipital, forehead?

big game hunting evidence

wooden spears and processed animal bones

400kya

Schöningen spearas

6-7.5ft in length

made of tough spruce stems

may have been used as javelins

debate surrounding heidelbergensis

• did it evolve simultaneously from H. erectus in europe, asia, and africa? or does it represent a distinct dispersal from Africa?

• is it a single reproductive community or multiple ecological species?

• should heidelbergensis in europe be thought of as a different species from homo neanderthalensis?

~400-300kya, european hominins diverged from those in africa

how did hominin bones get tin sima de los huesos chamber?

only possible access to SH chamber was deep, vertical conduit which was impossible to climb

• accumulated by carnivores (hominins were prey) → unlikely, tooth marks are rare, as are fossils of other likely prey

• mudflow or flooding?

• accidental causes?

• deliberate burial?

SH specimens foreshadow the neanderthals

largest cranial capcity: 1390cc

occipital bun

wide nasal aperture

midfacial prognathism

no chin

lifeways of SH inhabitants

2 dental absecesses, periodontal disease but no cavities on SH individuals

→ health of SH people: adults show possible cribra orbitalia, a sign of nutritional stress during childhood

patterns of bone breakage

different coloration = recent fracture

spiral pattern = fresh fracture

antemortem: before death

perimortem: around the time of death

postmorten: after death (when bone was dry), dry bone fracture

perimortem cranial fracture characteristics

no external beveling

internal beveling

radiating fracture line, depression fracture

cranium 3

• depressed and stellate fracture (radiating fracture lines)

  • endocranial view shows beveling

cranium 17

• fracture location (frontal left side) suggestive of face-face conflict

• similar dimensions of depression fractures 1 and 2 suggest they were caused by same object

  • forensic analysis suggest 2 separate impacts

Cranial breakage patterns at Sima de los Huesos

• 16/17 cranial individuals with postmortem (dry bone) breaks probably due to sediment pressure

• 8 also show several perimortem characteristics: oblique angle of fracture, smooth break surface, beveling, etc.

  • possible causes of perimortem breaks? → murder, violence, free fall?

possible causes of Perimortem breakage

violence

• results of repeated blows in violent encounter

• localized, depressed fracts less likely accidental

free fall

• would require the highly improbable occurrence of same object striking the skull twice

our newest cousin: homo naledi

330,000-230,000ya in south africa

phylogenetic position debated, unusual mosaic of traits

naledi’s mosaic of traits

small cranial capacity of 450-600cc

australopithecus like pelvis and shoulder

legs, hands, and feet more like later homo, except for curved finger bones

smaller teeth but very strong enamel

rising star cave

several very narrow points to reach the chamber (7.5in)

naledi remains found in dinaledi chamber

no tools or animal bones

underground astronauts

• Excavations conditions within cave were difficult to navigate

Berger posted a call of Facebook for researchers to come to South Africa at short notice: Master’s or PhD in paleoanthropology, Caving experience, Excavation experience, Must be able to fit through the cave openings, 6 women were selected

rising star workshop

large number of fossil specimens (>1500 pieces, 18 individuals)

Berger and team invited numerous early-career scholars to collaborate on morphology research

All data published open-access (e.g. 3D scans of fossils)

intentional burial?

Hypothesis heavily promoted in unreviewed pre-prints and media coverage

Claim: soil micromorphology suggests the holes were dug deliberately and bones were buried very quickly

• Originally accompanied by claims that Naledi produced rock art

• Burial article ultimately published, rock art rejected

naledi in space

Clavicle of A. sediba and hand bone of H. naledi sent into space with Virgin Galactic flight, Exported by PI for excavations of both fossils, Lee Berger

• Widely criticized for being irresponsible, pointless

• Meant as a gesture to promote South African science