Complex sentence: Cats' intelligence may have increased during their semi-domestication: urban living may have provided an enriched and stimulating environment requiring novel adaptive behaviours, although this scavenging behaviour would only have produced slow changes in evolutionary terms.
Split into simpler sentences: Cats' intelligence may have increased during their semi-domestication: urban living may have provided an enriched and stimulating environment requiring novel adaptive behaviours. This scavenging behaviour would only have produced slow changes in evolutionary terms.