Why is it argued that speech is only possible in modern homo sapiens and not in homo erectus or homo neanderthalensis? the brain wiring is not set up properly the capacity for language may be innate homo sapiens is the only species with a large enough oral cavity and a low enough larynx to allow for speech production. the areas for speech and sound recognition are not developed in other primates?

homo sapiens is the only species with a large enough oral cavity and a low enough larynx to allow for speech production. 

One line of evidence that speech only possible for modern homo sapiens is the anatomy of their throat. Speech depends on certain anatomical arrangements and the Homo sapiens is the only species with a large enough oral cavity and a low enough larynx that would allow speech.

9.9 years

a = p(1 + rt) . . account balance after time t at rate r starting with principal p

3000 = 2500(1 + 0.0202t) . . filling in the given numbers

1.2 = 1 + 0.0202t . . divide by 2500

0.2 = 0.0202t . . . subtract 1

0.2/0.0202 = t ≈ 9.901

it will take about 9.9 years for the account balance to reach $3000.

explanation:

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.