Subject: How did we get our big brains?

The anthropologist Marvin Harris mentioned this theory (by Fialkowski)
 as to what factors were behind the ballooning of our brains.
 Briefly,the idea is that since brain cells are especially
sensitive to heat stress, and early humans spent a lot of time
running around in the hot African sun (and are adapted to running;
no body hair, sweat through skin), having many brain cells
provided a kind of protective redundancy.  Information theory
says that the breakdown of a single unit is less likely to
crash the whole system if there is a redundancy of units.
    Have you heard of this?  Is it given credence today?
Thanks for taking my question

Re: How did we get our big brains?