The world's unsolved problems
993 open questions across 14 fields, gathered from Wikipedia. Pick one and start thinking.
Showing all 993 problems · surprise me
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Heritable components of homosexuality
How to reconcile evolution with the heritable components of human homosexuality? Homosexuality is prevalent across human societies, past and present. These facts constitute an evolutionary puzzle.
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Decline in average human body temperature since the 19th century
Medical data suggests that the average body temperature has declined 0.6 °C since the 19th century. The cause is unclear although it has been suggested that it has some relation with reduced inflammation from reduced exposure to microorganisms.
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Why are there blood types?
It is unclear what the origin and purpose of having blood types is. It is thought that O blood may be an adaptation to malaria and that different blood types respond to different diseases but this hypothesis has yet to be proven. Why did these antigens...
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Photic sneeze effect
What causes the photic sneeze effect? Why is it so common yet not universal?
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Human sex pheromones
There is contradictory evidence on the existence of human pheromones. Do they actually exist, and if so, how do they affect behavior?
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Existence of the Grafenberg spot (G-spot)
Does the G-spot actually exist? If so is it present in all women? What exactly is it?
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Extinction of archaic humans
Why did archaic human species such as Neanderthals become extinct, leaving Homo sapiens the only surviving species of humans?
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Love
When did pair bonding evolve? Is pair bonding an antecedent to romantic love, or have there been other steps in the evolution of pair bonds in humans (e.g. a seasonal bond)? A theory exists that romantic love evolved by co-opting the systems for...
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Neuroplasticity
How plastic is the mature brain?
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General anaesthetic
What is the mechanism by which general anesthetics work?
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Neuropsychiatric diseases
What are the neural bases (causes) of mental diseases like psychotic disorders (e.g. mania, schizophrenia), Parkinson's disease, Alzheimer's disease, or addiction? Is it possible to recover loss of sensory or motor function?
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Neural computation
What are all the different types of neuron and what do they do in the brain?
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Cognition and decisions
How and where does the brain evaluate reward value and effort (cost) to modulate behavior? How does previous experience alter perception and behavior? What are the genetic and environmental contributions to brain function?
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Computational neuroscience
How important is the precise timing of action potentials for information processing in the neocortex? Is there a canonical computation performed by cortical columns? How is information in the brain processed by the collective dynamics of large neuronal...
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Computational theory of mind
What are the limits of understanding thinking as a form of computing?
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Consciousness
What is the brain basis of subjective experience, cognition, wakefulness, alertness, arousal, and attention? What is the precise mechanism behind how phenomenal binding occurs? Is there a "hard problem of consciousness"? If so, how is it solved? What, if...
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Free will
Do humans or other organisms possess free will? Particularly studied by the neuroscience of free will.
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Language
How is it implemented neurally? What is the basis of semantic meaning?
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Learning and memory
Where do our memories get stored and how are they retrieved again? How can learning be improved? What is the difference between explicit and implicit memories? What molecule is responsible for synaptic tagging?
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The emergence and evolution of intelligence
What are the laws and mechanisms of new idea emergence (insight, creativity synthesis, intuition, decision-making, eureka); development (evolution) of an individual mind in ontogenesis, etc.?
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Perception
How does the brain transfer sensory information into coherent, private percepts? What are the rules by which perception is organized? What are the features/objects that constitute our perceptual experience of internal and external events? How are the...
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Paradox of the plankton. The high diversity of phytoplankton seems to violate the competitive exclusion principle.
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Ediacaran biota. How should Ediacaran biota be classified? Even what kingdom they belong to is unclear. Why were they so decisively…
Ediacaran biota. How should Ediacaran biota be classified? Even what kingdom they belong to is unclear. Why were they so decisively displaced by Cambrian biota?
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Cambrian explosion. What is the cause of the apparent rapid diversification of multicellular animal life around the beginning of the…
Cambrian explosion. What is the cause of the apparent rapid diversification of multicellular animal life around the beginning of the Cambrian, resulting in the emergence of almost all modern animal phyla?
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Darwin's abominable mystery of botany/plants. What is the exact evolutionary history of flowers and what is the cause of the apparently…
Darwin's abominable mystery of botany/plants. What is the exact evolutionary history of flowers and what is the cause of the apparently sudden appearance of nearly modern flowers in the fossil record?
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Adult form of Facetotecta. The adult form of this animal has never been encountered in the water, and it remains a mystery what it grows…
Adult form of Facetotecta. The adult form of this animal has never been encountered in the water, and it remains a mystery what it grows into.
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Origin of snakes. Did snakes evolve from burrowing lizards or aquatic lizards? There is evidence for both hypotheses.
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Origin of turtles. Did turtles evolve from anapsids or diapsids? There is evidence for both hypotheses.
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Paleodictyon
What is the origin of this trace fossil and its modern counterparts? Despite many theories proposed, no evidence has been found to confirm any of them.
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Francevillian biota
were they early multicellular organisms?
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Data last refreshed 2026-10-20 03:01 UTC.