Human footprints and "fingerprints" are visible in many places today, ranging from the skyscrapers that characterise modern cities to pyramids and other ancient monuments. Human activity is also defined by vast, cultivated fields and roads. What would the world look like if there were no humans? Some scientists describe a scene full of pristine wilderness where an abundance of species can be observed. For example, "vast areas covered in rich vegetation, inhabited by many different animals". A world without the presence of modern humans would also mean that our distant ancestors – the Neanderthals – would still be roaming the expanses of the Earth.