Elephants are the smartest land animals on earth and the complexity of their brains is comparable to that of humans. This is also clearly reflected in their behaviour. They are able to communicate with body language within their own species and even with humans, and a recent study has shown they even give each other names.
Dolphins and whales are also pretty smart, so yes, size is a big part of what matters.
their brains are a lot smaller though, so less complex
If size is what matters, then whales, elephants, and dolphins all have more complex brains than humans.
Elephants are the smartest land animals on earth and the complexity of their brains is comparable to that of humans. This is also clearly reflected in their behaviour. They are able to communicate with body language within their own species and even with humans, and a recent study has shown they even give each other names.
Dolphins and whales are also pretty smart, so yes, size is a big part of what matters.