Love is in the air today and it's all down to chemistry.

Sussex University professor of theoretical chemistry, Malcolm Heggie, will explain to visitors at the Brighton Science Festival how our chemical make-up affects our relationships.

His talk, called A Scent of Man: The chemistry of smell, taste and sex, discusses how much of human behaviour is more a question of science than art.

He said: "Why do we have the senses of smell and taste, how do they operate and are there smells which play a role in human relationships?

"Humans are complex beings.

"Relying on pheromones might be a good idea if you want to attract an ant but women are often rather more sophisticated.

"There are two trains of thought.

"One is pheremones - chemicals from one animal which control another animal's behaviour.

"They are crucial for lower animals because they have to do exactly what the pheremones say.

"But it's arguable whether they actually do have an affect on humans because we have this huge layer of conscienceness in our frontal lobes.

"What we can say is that smell has an direct connection with the ancient part of the brain, called the limbic system.

"That's the part of the brain where we distinguish between agreeable and disagreeable.

"It controls all the emotions, such as passion, love, joy and sadness.

"For relationships to work, it is certain that the chemistry has to be right."

Mr Heggie will also answers other questions relating to how science affects everyday life, such as: Why is seaweed soup so delicious? and why does mustard get up my nose?

He said: "About 80 per cent of taste is down to smell.

"The tastes we have are sweet, salty, bitter and sour but there is also another one called umami that is the overall enhancement of taste.

"There is also a class of smells or tastes which are nerve stimulants, such as horse radish and mustard.

"This is because they contain capsaicin, which is a component of chili.

"I will talk about how our taste has evolved as a matter of nutrition and safety.

"For example, bitter things were usually poisonous and sweet things nutritious.

"I will also talk about chemical smells such as alcohol."

The talk will be held as part of the Brighton Science Festival at Brighton City College, Pelham Street, on Sunday, February 26, at 8.30pm.

For more information about the festival and the talk visit www.brightonscience.com