Complex sentence: The Mulefa's less advanced technology may be due to their limited trunks--the versatility and dexterity of hands gives humans an advantage; the fact that their natural environment supplies them with everything they need, may also preclude any need for further development.
Split into simpler sentences: The Mulefa's less advanced technology may be due to their limited trunks--the versatility and dexterity of hands giving humans an advantage. The fact that their natural environment supplies them with everything they need, may also preclude any need for further development.