Words R Us

The robust australopithecines all became extinct between 1.5 and 1 million years ago, while one of the gracile autralophithecines is believed to have given rise to the branch leading to the emergence of the genus Homo c.2.5 million years ago.

Early transitional humans had brains that on average were about 35% larger than those of Australopithecus africanus

chimpanzees 300-500 australopithecines 390-545 early transitional humans 509-752 modern humans 900-1880

“Gestures are used across a wide range of contexts whereas most facial expressions and vocalizations are very narrowly used for one particular context,”

Although all primates use their voices and facial expressions to communicate, only people and the great apes — chimpanzees, bonobos, orangutan and gorillas — use these types of gestures as well. De Waal noted that great apes first appeared about 15 to 20 million years old, meaning such gestures may have been around that long. “A gesture that occurs in bonobos and chimpanzees as well as humans likely was present in the last common ancestor,” Pollick said in a statement. “A good example of a shared gesture is the open-hand begging gesture, used by both apes and humans.” This last common ancestor may date to about 5 million to 6 million years ago.

He added that when the apes gesture, they like to use their right hands, which is controlled by the left side of the brain — the same side where the language control center appears in the human brain.

An important insight from NCT is that acquired characters play an evolutionary role, through transforming selective environments. This is particularly relevant to human evolution, where our species appears to have engaged in extensive environmental modification through cultural practices. Such cultural practices are typicaly not themselves biological adaptations (rather, they are the adaptive product of those much more general adaptations, such as the ability to learn, particularily from others, to teach, to use language, and so forth, that underlie human culture) and hence, cannot acurately be described as extended phenotypes (1). Mathematical models reveal that niche construction due to human cultural processes can be even more potent than gene-based niche construction, and establish that cultural niche construction can modify selection on human genes and drive evolutionary events (2-4). There is now little doubt that human cultural niche construction has co-directed human evolution in this manner (5)

one primary objective of this study was to examine the relationships among gesture, speech production, and listener comprehension. In doing so, we address two questions: First, do gestures enhance listener comprehension? Second, if gesture enhances comprehension, how does it do so? Does gesture have a direct effect on listener comprehension, or does gesture enhance listener comprehension only because it aids the speaker in producing more effective speech? Thus our first objective in this study was to examine the extent to which gesture enhances listener comprehension and the extent to which this relationship is mediated by the effect of gesture on speech production.

they gesture more on certain types of words or phrases. For example, Rauscher et al. (1996) found that gesturing was nearly five times more frequent on "spatial content phrases" (phrases containing spatial prepositions such as "under" and "on") than on nonspatial phrases. Moreover, they found that not being able to gesture was more damaging when the speaker attempted to convey spatial content. Therefore, a second objective of this study was to examine whether gesture (or not being able to gesture) is more important for some types of speech than for others.