try forceing wheat to be birthed. or bos taurus can work.

but H. erectus want cooler temperatures so maybe try to create uplands with lots of conifers and overal ice age fauna and flora like mamoths and smilodons. humans in general like wide arears with edible plants like as mentioned wheat and some other plants like olea (olives) and maize (corn).

without knowing how youre cube is planed or wath temputure is it at i cant do much. a screenshot coud help!