Hallowe’en special – Natural Vampires

Carole Jahme explains the natural inspiration for her new vampire novel in conversation with BBC natural history filmmaker Dr Paul D Stewart. 


Carole Jahme explains the natural inspiration for her new vampire novel Worth Their Weight in Blood, in conversation with BBC natural history filmmaker Dr Paul D Stewart


PS: I liked the idea [in your book Worth Their Weight in Blood] that the vampires ‘don’t see themselves’ in a mirror because they have a different form of self-awareness. It even feeds in to the concept of their lacking a ‘soul’. 

The ‘mirror test’ has been used to study human autism and social empathy. Can someone really be functionally ‘intelligent’ and not recognise themselves in this way? And how does this compare to the social awareness of other primate species?   

CJ: We know an autistic person’s self-relatedness is different. In one mirror study young autistic children spent less time looking at their own faces and the faces of others, and less time using the mirror to be social, than non-autistic children. Instead they spent more time looking at the reflection of objects and experimenting with the mirrow as an object by moving it.

Great apes exhibit a different kind of social awareness from each other. Gorillas behave differently to chimpanzees, which in turn behave differently to orangutans and bonobos.

In some instances, chimpanzee emotional intelligence exceeds the social perception of some autistic humans. This important fact supports the campaign against using apes in laboratory experiments.

Tests on bonobo emotional intelligence indicate they are more empathically sophisticated than chimps.

PS: As wolves in sheep’s clothing, your vampires use their intelligence to move stealthily among their more numerous prey. What examples from nature inspired you? 

CJ: Deceit is rife throughout the natural world and we regularly deceive ourselves – for instance, the placebo effect is well documented. Among insects there are some gruesomely cunning examples of predatory disguise and if you imagine these little critters at human-size with human intellect it’s an utterly terrifying concept.

For example, the large blue butterfly caterpillar secretes sweet fluid to attract red ants. The ants carry the caterpillar into their colony where they use their antenna to massage the caterpillar, eliciting ‘honeydew’ (derived from its diet of thyme and marjoram flowers), which the ants lap up.

After about 20 days the caterpillar hibernates within the ant nest. But when it awakes it has changed and it is no longer a vegetarian. It now wants meat and uses olfactory disguise and audible mimicry to enable it to creep into the ant nursery where it preys upon the ants’ precious eggs and larvae.

Sounding and smelling like an ant, its murderous subterfuge goes undetected and the large blue remains in the ant nest until it pupates.

Around 20 days later, the adult butterfly emerges and a band of ants carefully carry the sticky butterfly out of their nest and into nearby foliage, where the ants stand guard against spiders while the vulnerable butterfly sits on a leaf waiting for its wings to dry.

Once the butterfly is safely airborne the ants return to the colony. There is something distinctly vampiric about the large blue’s ability to seduce, predate and sucker a whole colony of ants.

PS: In Worth Their Weight in Blood vampires can infect normal humans. Indeed the DNA for vampirism could be considered a virus like a parasite that replicates by inherited and lateral infection and then drives behaviours that ensure its genetic survival. Do you think something like that could really work?  

CJ: Yes, as the brain is the control centre, any virus that can reprogramme cognition could cause all manner of self-serving behaviours.

With the rabies parasite, the damage to the host’s nervous system usually results in death, but until that point the sufferer’s behaviour is radically altered. The virus grows in the host’s brain and salivary glands, and rabid animals are driven to bite, thus passing on the rabies virus.

The Toxoplasma gondii parasite usually attacks rodents’ brains, nullifying their fear of cats. Once the infected rodent is eaten the parasite breeds inside the cat. The cat’s faeces contain the parasite, which then infects another rodent and so the cycle continues.

But sometimes the Toxoplasma parasite attacks humans. Infected people manifest a slower response and are significantly more accident prone.


The zombie parasitic fungus (Cordyceps) is over 48 million-years-old. Today it usually infects carpenter ants and controls their behaviour, causing the ant to leave the nest, climb up foliage and bite into the main vein of a leaf, lock its jaws and die in this position. Later the fungus grows out from the ant’s head and releases its spores to infect more ants.

Carole Jahme was interviewed by Dr Paul D Stewart for this blog.

Paul Stewart is a zoologist and multi-award-winning BBC natural history filmmaker. Carole Jahme is an author and science writer for the Guardian.

Find out more about Carole’s new Darwinian vampire novel Worth Their Weight in Blood.