Humans are endowed with the capacity to create language in two different physical channels: spoken and signed. This embarrassment of riches, unique to humans, allows us to probe the most fundamental questions about language and its origins.
By examining the structure of sign languages, including a newly emerging Bedouin Sign language, the talk addresses these questions: How much of our language capacity is inborn, and how much can be attributed to usage with others? Does language start out simple or complex? Does the nature of the physical channel shape linguistic structure in nontrivial ways? Finally, how multi-modal is our language capacity -- do all languages, whether spoken or signed, include gestures? The talk aims to offer some answers, and to trigger ideas for future research.