Why does winston feel that the man sitting next to him in the cafeteria is not real human being but some kind of dummy?

that might be true as some of the "humans" are not really human

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.