Intelligence in Nature - Jeremy Narby [82]
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P. 80: SIZE OF HUMAN CORTEX
Passingham (2002) writes: âIt was argued long ago that what may be critical for intelligence is the absolute amount of tissue (or number of neurons) above that accounted for by the general relation between brain size and body size. Larger bodies require larger brains, but for any particular body size the different mammalian groups differ in brain size, with the primates having especially enlarged brains. The human neo-cortex is over three times as large as expected for a primate matched for body size. Even though the present study shows that the human frontal lobes do not differ as a proportion of the neo-cortex, they are over three times larger than would be expected for a hypothetical great ape of the same body weight. Such a difference must be of immense consequence for our capacity to plan and reasonâ (pp. 191â92). The quotes in the main text are from Carter (1998, p. 35) and Greenfield (2000, p. 164).
CHAPTER 7
P. 83: PLANTS CRY FOR HELP
Whitfield (2001) writes: âPlants cannot run from trouble, but neither do they lie down and surrender. As well as producing a variety of noxious chemicals to deter herbivores, they can enlist help from higher up the food chain, releasing volatile chemicals that attract predators to eat the creatures that are eating themâ¦Researchers estimated that, by releasing volatiles, tobacco plants could reduce the number of herbivores attacking them by more than 90 percentâ (pp. 736-37). Buhner (2002) writes: âIn response to overfeeding by aphids some plants will release a volatile aromatic, E-beta-fanesene, from their leaves. This mimics an aphid alarm pheromone warning of approaching predators, telling them to flee the plant. Spider miteâinfested lima beans will release a blend of volatile oils (terpenoids) that attracts a predatory mite that feeds on spider mites. The plants can tell exactly what kind of mite is feeding on them through analyzing the chemistries of their saliva. Each plant species then produces a different blend of volatiles depending on what kind of spider mite is feeding on it. That mix will only call the predator that feeds on that kind of mite. The plants also tell other, uninfested, lima beans what is happening. Those receiving the communication also begin to release the chemical that calls predatory mites, thus reducing the spread of the feeding mitesâ (p. 162). Marcel Dicke, who first carried out the research on mites and lima beans is quoted by Russell (2002): âToday, the scientific community agrees that plants talking to their bodyguards is likely to be a characteristic of most, if not all, plant speciesâ¦If plants talk to their bodyguards, then why would their neighbors not take advantage of that and eavesdrop on the message? The topic of plant-to-plant communication is back on the agenda, and the evidence is accumulatingâ (p. 49). Ryan (2001) writes: âVolatile chemicals are the language of plants. Through the smell of fresh blossoms, good coffee