Related Experiment Video
Updated: Jun 26, 2026
08:30
Imaging Odor-Evoked Activities in the Mouse Olfactory Bulb using Optical Reflectance and Autofluorescence Signals
Published on: October 31, 2011
The evolution of consciousness: Olfaction first, vision later?
1London School of Economics and Political Science, London, UK j.birch2@lse.ac.uk https://personal.lse.ac.uk/birchj1/.
The Behavioral and Brain Sciences
|June 24, 2026
Summary
Conscious vision may have evolved after, not before, other senses. An olfaction-first model explains how consciousness integrates information over time, around 400 milliseconds.
Area of Science:
- Neuroscience
- Evolutionary Biology
- Philosophy of Mind
Background:
- Theories on the evolution of consciousness often place vision first.
- Alternative hypotheses suggest other sensory modalities may have played a foundational role.
Purpose of the Study:
- To propose and evaluate an "olfaction-first" model for the evolution of conscious experience.
- To contrast this with a "vision-first" evolutionary narrative.
Main Methods:
- Theoretical modeling of sensory integration mechanisms.
- Analysis of the temporal dynamics of conscious processing.
Main Results:
- An olfaction-first hypothesis provides a coherent framework for understanding consciousness.
- This model effectively explains the link between consciousness and holistic integration within specific temporal windows (around 400ms).
Conclusions:
- Conscious vision might have co-opted pre-existing integrative mechanisms initially developed for olfaction.
- This challenges traditional vision-centric views on the evolution of consciousness.
Related Concept Videos
01:25Olfaction
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The olfactory receptors are embedded in the cilia of the...
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01:20Physiology of Smell and Olfactory Pathway
Humans detect odors with the help of specialized cells located in the upper part of the nasal cavity, called olfactory receptor neurons (ORNs). ORNs possess hair-like structures called cilia, which are receptive to sensations from the inhaled air. When an odorant molecule binds to a specific receptor on the cell of the cilia, it leads to a series of events that ultimately cause the ORN to send electrical signals to the olfactory bulb in the brain through the olfactory nerves.
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01:24Vision
Vision is the result of light being detected and transduced into neural signals by the retina of the eye. This information is then further analyzed and interpreted by the brain. First, light enters the front of the eye and is focused by the cornea and lens onto the retina—a thin sheet of neural tissue lining the back of the eye. Because of refraction through the convex lens of the eye, images are projected onto the retina upside-down and reversed.
01:26Introduction to Special Senses
Sensory receptors play an integral part in comprehending our external and internal environments. They receive diverse stimuli, converting them into the nervous system's electrochemical signals. This conversion occurs as the stimulus alters the sensory neuron's cell membrane potential, instigating the generation of an action potential. This action potential is subsequently transmitted to the central nervous system (CNS), which integrates with other sensory data or higher cognitive functions.
01:11Sensory Perception: Organization of the Somatosensory System
The somatosensory system is the central and peripheral nervous system component that senses and processes touch, pressure, pain, temperature, and body position or proprioception. The process of sensation takes place at three levels:
The receptor level:
The receptor level is the first stage of sensation. It involves the detection of a stimulus by specialized sensory receptors. The stimulus must arrive within the receptor's receptive field. Next, the receptor converts the energy of the stimulus...
The receptor level:
The receptor level is the first stage of sensation. It involves the detection of a stimulus by specialized sensory receptors. The stimulus must arrive within the receptor's receptive field. Next, the receptor converts the energy of the stimulus...
01:03Olfactory Receptors: Location and Structure
The process of olfaction, also known as the sense of smell, is a sophisticated chemical response system. The specialized sensory neurons that facilitate this process, known as olfactory receptor neurons, are situated in an upper segment of the nasal cavity, known as the olfactory epithelium. Olfactory sensory neurons are bipolar, with their dendrites extending from the epithelium's apex into the mucus that lines the nasal cavity. Airborne molecules, when inhaled, traverse the olfactory...