I can provide some information on the topic.
The evolution of intelligence is a complex and unpredictable process that depends on various factors, including environmental conditions, genetic mutations, and natural selection. If humans were to disappear, it is uncertain which species, if any, would evolve to develop human-level intelligence.
Orcas (also known as killer whales), chimpanzees, and certain bird species have demonstrated remarkable cognitive abilities in their own right, but these abilities have evolved to suit their specific ecological niches and survival strategies. Each species has unique cognitive strengths and limitations, shaped by millions of years of evolution.
Chimpanzees are our closest living relatives, sharing approximately 98% of their DNA with humans. They exhibit problem-solving skills, tool use, social complexity, and some capacity for language-like communication. If any species were more likely to develop higher intelligence after humans, chimpanzees could be considered strong candidates due to their genetic similarity and existing cognitive capabilities.
Orcas are highly intelligent marine mammals, known for their sophisticated social structures and complex hunting techniques. They exhibit problem-solving abilities and have large, highly developed brains. However, their environment and physical limitations as marine creatures might influence the direction of their evolutionary path differently from terrestrial species.
Certain bird species, such as corvids (e.g., crows and ravens) and parrots, have shown remarkable problem-solving skills and tool use, and some have demonstrated the ability to communicate and even use syntax in their vocalizations. However, the structure of bird brains is different from mammals, and their evolution may follow a distinct trajectory.
Ultimately, predicting the evolution of intelligence in the absence of humans is speculative and challenging due to the countless variables involved. The emergence of human-level intelligence required a unique combination of circumstances over millions of years of evolution. If humans were to disappear, the trajectory of evolution could take countless paths, and the outcome is uncertain.