another Burgess Shale organism of uncertain affinity, known as 

 Opabinia. According to the reconstruction and interpretation pro- 

 vided by Briggs et al. (1994). Opabinia had five large eyes at the 

 front of the head and a long flexible proboscis that ended in an array 

 of grasping spines used to capture prey as the animal swam rapidly 

 over the seafloor relying on its lateral lobes for propulsion and using 

 its tail as a stabilizer. 



Throughout 500 million years of animal evolution, every advance 

 that a predator could make to its effectiveness as a hunter had to be 

 countered by comparable improvements in the survival ability of its 

 prey, if one or the other were to avoid extinction. In this way, sense 

 organs and coordinating neural systems were under constant selec- 

 tive pressure to promote their improvement. Cranial expansion by 

 hominids faced with completely new and unprecedented predatory 

 challenges appears to have been one of the solutions. 



A Glimpse of How Early Humans Started to Overcome the Threat 

 of Predation 



There can surely be no doubt that humans eventually established 

 their current dominance in the natural world through intelligence 

 and its product, technology. But were the initial steps along this 

 path also mediated in this way? I have the impression that some of 

 the evidence from the Swartkrans cave confirms this possibility. 



Excavation revealed that the Member 3 deposit accumulated in a 

 roofed erosional gully, about 20 m long and up to 5 m wide, running 

 between the west wall of the cave and a vertical bank of older 

 sediments on the east side of the gully. Initially I was not aware 

 that the calcified sediment in this gulley was different from that 

 further to the east, but when pieces of burnt bone started turning up 

 with regularity, suspicions were aroused and a near-vertical uncon- 

 formable contact became apparent between the contents of this gully 

 and what surrounded it. The excavation proceeded to a depth of 850 

 cms and produced 59.488 pieces of fossil bone, including 9 fossils 

 of robust australopithecines. and 270 pieces of bone that showed 

 signs of having been burnt. Careful chemical and histological ex- 

 aminations confirmed that the bones had been exposed to fire and 



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