Wanted to add a bit more, since I now found a bit more knowing that this is called a simian line.
A passionate idealist I would say, one who is likely to succeed and maybe bring about change since they seem to not be accepting of rules of society or may think in different terms about the world at large than most people. Seem to be intense and be able to feel their ideals.
In some cases the lines of Heart and Head are not separate at all, but join together to form one line running straight across the entire palm. This is known as the Simian Line. (Also called the "Simian Crease", "Simian Fold", and "Transverse Palmar Crease")
When the Simian Line occurs, the "Great Quadrangle" is entirely missing. There is no distinction between what is desired (the Heart) and what is thought (the Head). The result is an incredible intensity of nature, but a strong tendency to rush into all things without thinking them through.
Also note that without the Great Quadrangle, we have a completely closed-minded individual. Because they are so focussed on a particular thought, all else is excluded.
In another possible appearance of the Simian Line, the lines of Head, Heart, and Life are all joined. All the above traits apply, but even more intensely, since there is now no distinction between the thoughts, desires, and life itself.
The Simian Line gives the ability to focus on one thing, absolutely, to the exclusion of all else. These people generally achieve and accomplish far more than most, developing techniques and inventions that will last for generations. They also experience far more misfortune than most, usually due to the same intensity that drives them. A truly double-edged sword.
http://www.humanhand.com/simian.html Many of those with a simian line reject the belief systems they grew up with to accept another, often radical, faith. This kind of absolute change is often seen in other areas of life as well—in a career or lifestyle change, for instance, where the break with the old and the acceptance of something totally new and foreign is radical and thorough.
The simian line reveals that all the passion of the heart line is channelled into whatever purpose the intellect chooses. It shows great determination and a sense of purpose, and gives an individual a marked determination to get their own way. It grants tremendous powers of concentration and the ability to focus on realizing goals.
The simian line is found on the hands of those who have had to overcome hardship, a difficult start in life, or troubled periods later, and of those who have had to find and draw on vast reserves of passion and willpower to do so. The emotions have become one with the intellect, so that the mind and heart work in unison, to overcome tests and challenges. It is the mark of a survivor.
Those with a simian line love or hate with equal intensity. It does not pay to oppose them unless you are sure of your facts.
Those with a simian line are strongly attached to nature, and you will often find them working with animals. In addition, there is a strong appetite for a home... and they are loyal and expect loyalty in return. These people are survivors in the original sense, which means they are pragmatic—and just a little suspicious of others. ...They are salt of the earth, and many have wonderful senses of humor ..they value their privacy and are fiercely protective (sometimes too protective) parents
Therefore, people with a Simian line are strongly passionate about their ideals, investing the energies of both heart and head in everything they do. They often become activists, campaigners, or sometimes champions of lost causes. When entering a job, activity, or relationship, both their heart and mind have to be satisfied. Otherwise, they suffer stress and unhappiness as their heart and head constantly argue.
People with Simian Lines are filled with restless energy. There are no half measures with them. Everything they do is done with purpose and drive. This energy can be released through hard work or dynamic sports like tennis or hockey. A person with this line does everything with gusto, concentrating on the task at hand and plugging away until its completeion.
One of the ways to release this energy is through creative endeavors. The owner of a Simian Line feels relaxed when he is focused on creativity. Those who enjoy working with their hands get involved in building houses or furniture. Mentally inclined people with this line write books, music, or poetry. Any person with even a trace of artistic talent plus a Simian Line will feel rewarded by painting, drawing, or designing. So keep in mind that the Simian Line is an indication of a creative drive. In any group of artists, the chance of finding a Simian Line is higher than in any random group of people.
If you’re dating a Simian Line guy, keep in mind that he will have strong opinions. Imagine if every little thing that popped into your head registered immediately in your heart. This is a reality for a Simian Line person due to their Head and Heart lines being one. If he starts to speak about a crooked politician his heart rate will rapidly increase and he may start to shout.
http://www.jenniferboyer.com/SimianlineFacts.html