Assuming the Out-of-Africa hypothesis, total phoneme inventory necessarily depends not just on distance to the origin but also on the speaker population size. By minimizing the residual sum of squares over continental Africa, find the bestfitting origin under the linearity assumption

\[
E\left(\operatorname{Tnpd}_{i}ight)=\beta_{0}+\beta_{1}\left\|x_{i}-x_{0}ight\|+\beta_{2} \log \left(\operatorname{popn}_{i}ight) .
\]

You should not assume that the best-fitting origin lies in or near the box \(9-10^{\circ} \mathrm{E}\), \(1-2^{\circ} \mathrm{S}\).